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A DEHYDROGENATION AND DEHYDROCYCLIZATION CATALYST, ITS SYNTHESIS AND USE

This invention relates to a dehydrogenation and dehydrocyclization catalyst, its synthesis and use.

Naturally occurring and synthetic crystalline microporous materials have been demonstrated to exhibit catalytic properties for various types of hydrocarbon conversions. The term "crystalline" used to refer to these materials relates to the ordered definite crystalline structure of the material which is unique and thus identifiable by a characteristic X-ray diffraction pattern.

The term "microporous" as it refers to such material relates to pores, or channels, with diameters of less than 20

Angstroms. Examples of these microporous crystalline materials include crystalline silicates, crystalline aluminosilicates, crystalline aluminophosphates (ALPOs), crystalline silicophosphoaluminates (SAPCs) and related compositions and intercalated pillared materials derived from clays, layered silicates and titanates. Crystalline silicates, alumino silicates, ALPOs and SAPOs, have pores of uniform size and channel systems which are uniquely determined by the unit structure of the material. The uniform pore size and/or channel systems allow such materials to selectively absorb molecules of certain dimensions and shapes.

Microporous crystalline materials having pores, or channels, of less than 20 Angstroms, can be divided into small, medium and large pore by the diameters of those pores, or channels. The pores of the small pore material have an average diameter of less than 5 Angstrom; medium size pores range from an average diameter of 5 to 7 Angstrom, and large pore materials indicates a diameter of greater than 7 Angstrom. The word "average" is used to refer to diameter to embrace those species in which the pore is elliptical. Alternatively, the demarcation between small, medium,

and large pore materials can be based on the following sorption properties (measured at room temperature for crystallites having a minimum dimension of 0.1 micron):

1. Small pore: n-Cg/i-Cg sorption ratio greater than approximately 10.

2. Medium pore: n-Cg/i-Cg is less than 10 and n-C ₀ /Mesitylene sorption ratio greater than approximately 5.

3. Large pore: n-Cg/Mesitylene sorption ratio less than approximately 5. In the art, zeolites are a subclass of crystalline microporous silicates. Zeolites can contain aluminum as well as silicon. In some zeolites, the upper limit of the silicon/aluminum atomic ratio is unbounded. ZSM-5 is one such example wherein the silicon/aluminum atomic ratio is at least 2.5 and up to infinity. By way of illustration, Uhited States Patent No. 3,941,871, reissued as RE 29,948, discloses a porous crystalline silicate made from a reaction mixture containing no deliberately added aluminum and exhibiting the X-ray diffraction pattern characteristic of ZSM-5 zeolites. Zeolites can be acidic or non-acidic, depending on the framework aluminum content and on the amount of compensating

+ + cations, such as Na , K , etc. ALPOs described in U.S. Patent

No. 4,310,440 are neutral. SAPOs described for example in U.S.

Patent No. 4,440,871 can be acidic or non-acidic depending on the ratio of framework A1:P therein and the compensating cation, such as Na , (other than proton species and other than proton forming species such as H4). ELAPOs are described in U.S. Patent No. 4,500,651, while MeAPOs are described in U.S. Patent Nos. 4,544,143 and 4,567,029. It has now been discovered that certain non-acidic crystalline microporous materials containing selected metal modifiers and a dehydrogenation metal exhibit high selectivity for dehydro enation and/or dehydrocyclization of paraffins. Moreover, while exhibiting that high selectivity for paraffin

dehydrocyclization, these compositions exhibit decreased selectivity for hydrogenolysis (especially methane formation) relative to their counterparts in which the modifying metal is absent. 5 Accordingly, the invention resides in one aspect in a catalyst composition comprising a hydrogenation/dehydrogenation metal , and a non-acidic crystalline microporous material containing indium , tin , thallium or lead.

The catalyst of the invention comprises a hydrogenation/

10 dehydrogenation metal and a non-acidic crystalline microporous material containing a metal modifier selected from indium, tin , lead and thallium As catalysts these non-acidic compositions exhibit extremely high selectivity for paraffin dehydrogenation and/ or dehydrocyclization reactions .

15 The amount of dehydrogenation metal in the catalyst can range from 0.01 to 30 weight percent and preferably 0.1 to 10 weight percent of the modified crystalline material . In a preferred embodiment , platinum is the hydrogenation/dehydrogenation metal . However, the hydrogenation/ dehydrogenation metal can be any Group

20 VIII metal including those of the platinum group (namely platinum, palladium, osmium, ruthenium, iridium and rhodium) , chromium and vanadium .

The metal modifier content of the crystalline materials can range from 0 .01 to 20 weight percent , preferably from 0 .1 to 10

25 weight percent . The modifier is selected from indium, tin , lead and thallium. Preferably, at least part of the modifier present forms part of the framework of the parent crystalline material .

The microporous crystalline materials of the invention are crystalline in the sense that they have identifiable structures

3.0 characterized by unique X-ray powder diffraction patterns .

Typically, the microporous crystalline materials have an X-ray diffraction pattern which corresponds to a zeolite , a silicophosphoaluminate (SAPO) , or an aluminophosphate (ALPO) . Prefereably, the crystalline material has the structure of ZSM-5 ,

ZSM-11, ZSM-12, ZSM-23 , ZSM-48 , ZSM-50 , zeolite Beta , ZSM-20 , SAPO-5 or ALPO-5. These materials have pore sizes up to 8 Angstrom and have X-ray diffraction patterns which are well known from the patent literature. In a preferred embodiment the pore size of the microporous crystalline material ranges from 5 to 8 Angstrom.

Where the crystalline material of the invention is an aluminosilicate zeolite , it will generally have a silica/ alumina molar ratio of at least 12 , but may in some cases have a silica/ alumina molar ratio up to 1000 , or greater. Preferably the zeolite contains less than 0.1 weight % aluminum. Moreover the zeolite may contain other elements than the metal modifiers and the basic framework elements silicon and aluminum, such as boron , iron, chromium and gallium. The content of these other elements in the crystalline material can range from 0 to 10 weight percent . When the crystalline material of the invention is a zeolite, preferably at least ^' some of the dehydrogenation metal is intrazeolitic, that is , some of that metal is within the pore structure of the crystal , although some of the metal may be on the surface of the crystal . A test for determining whether, for example, Pt is intrazeolitic or extrazeolitic in the case of ZSM-5 is reported by P.. M. Dessau , J. CATAL. Vol . 89 , p. 520 (1984) . The test is based on the selective hydrogenation of ole ins .

The catalyst compositions of the invention comprising hydrogenation/dehydrogenation metal combined with a metal modified microporous crystalline material is characterized by a lack of any appreciable acid activity. These catalysts therefore meet the criteria of non-acidic catalysts described by Davis and Venuto , J. CATAL. Vol . 15 , p.363 (1969) . Thus , a non-equilibrium mixture of xylenes are formed from either n-octane or each individual methylheptane isomer, with the n-octane yielding mostly o-xylene and

2 -methyl- heptane yielding mostly m-xylene, at conversions between and 10 and 60% . An additional method of testing the non-acidic character of the catalyst compositions of the invention is to add

100 mg of the catalyst to 30 ml distilled deionized water ( with a pH of 7) maintained under an inert atmosphere (i.e. free of C0 ₂ ) _. such as an argon atmosphere, whereby with the non-acidic composition of the invention the water will have a pH of at least 6 and preferably greater than 7.

When used to effect dehydrogenation of paraffins, for example, to aro atics, the catalyst compositions of the invention decrease the hydrogen content of the feed to produce a product having the same number of carbon atoms as the feed. In contrast, equivalent catalyst compositions free of the modifier also catalyze hydro enolysis of paraffins, e.g., to methane, as a major competing side reaction; and, accordingly, the latter compositions exhibit decreased selectivity for the aromatization of paraffins but increased selectivity for ^~ ι~ ^~ - paraffin production. Some of the aforementioned catalysts were screened for heptane aromatization at 538°C in the presence of nitrogen diluent. The results are shown in Table A below:

Table A Heptane Aromatization over Non-acidic Pt/ZS^5^ ^a J

(a) 30 torr (4 kPa) n-heptane in N ₂ at 538°C and 1 atm (100 kPa) total pressure; selectivities on ^ -free weight basis .

The non-acidic platinum catalysts, prepared from ZSM-5 modified with In, Sn, Pb and Tl provided much higher aromatics selectivity than all the other catalysts examined. Toluene selectivity from heptane was greater than 85 % at 99% conversion H ₂ free carbon basis) . The other catalysts , including Pt/E-ZSM-5 and Pt/high silica: alumina ratio ZSM-5 , also exhibited no appreciable acid activity so that platinum chemistry dominated. However, with these other catalysts , although significant metal-catalyzed aromatization was observed , hydro genolys is to methane constituted a major competing side reaction. The highest toluene selectivity from n-heptane observed was less than 50% , and in most cases that selectivity was significantly lower.

The metal modified crystalline materials of the invention can be made in various ways and, for convenience, the ensuing description will refer to production of indium-containing materials . Similar techniques can, however, be employed to produce materials containing tin , lead and/ or thallium.

Indium incorporation can be during synthesis or post-synthesis; and the materials can be prepared either by stepwise or simultaneous incorporation of the indium and the hydrogenation/dehydrogenation function to the crystallization reaction product. The dehydrogenation function can be first introduced to the synthesis product with subsequent indium incorporation , or vice versa. Stepwise preparation includes techniques of cocrystallization (by inclusion of an indium compound in the synthesis mixture used to produce the crystalline material) , impregnation , or ion exchange. Simultaneous incorporation includes the combination of indium ^" with the dehydrogenation/hydrogenation function during synthes is (i .e. , crystallization) or simultaneously after synthesis of the crystalline material .

An indium free material can be treated with indium compounds at elevated temperatures . .Such treatments can be conducted so that the source of indium is either in the gaseous

phase (such as indium chloride) or the liquid phase including the aqueous phase (such as indium nitrate). Alternati ^v ely, an indium free crystalline material can simply be impregnated with an indium source and then calcined at temperatures above 400°C. In the materials of the invention, all cation-exchangeable sites are occupied by cations other than hydrogen and other than hydrogen precursors, such as NH _* . Specifically, such sites are occupied by Na , K , Cs , Ca , Mg , Ea , Sr , or admixtures thereof, although some sites may of course be occupied by the metal modifier or hydrogenation/dehydrogenation metal. The alkali metals serve to neutralize any acidity due to framework aluminum. The source of alkali metal cation can derive from cations incorporated during synthesis, in excess of the aluminum content thereof. Alternatively, one can treat the final product with a basic solution of an alkali metal hydroxide as a final step prior to use, as described for example in U.S. Patent Mo. 4,652,360.

The metal modifier and dehydrogenation metal containing materials of the invention can be combined with a matrix or binder material to render them attrition resistant and more resistant to the conditions to which they will be exposed during use in hydrocarbon conversion applications. The combined compositions can contain 1 to 99 weight percent of the materials of the invention based on the combined weight of the matrix (binder) and material of the invention. When used in dehydrogenation and/or dehydrocyclization, the material of the invention will preferably be combined with low acidity matrix or binder materials, such as oxides of Groups IVA and IVB of the Periodic Table, most preferably silica. The catalyst co postion of the invention is useful for the dehydrogenation of hydrocarbons having at least 2 carbon atoms, and in particular for dehydrocyclization of aliphatics containing at least 6 carbon atoms. Examples of such reactions are discussed below.

Peforming

Catalytic reforming is a well known process in which hydrocarbon molecules are rearranged, or reformed in the presence of a catalyst. The molecular rearrangement results in an increase in the octane rating of the feedstock. Thus, during reforming low octane hydrocarbons in the gasoline boiling range are converted into high octane components by dehydrogenation of naphthenes and isomerization, dehydrocyclization and hydrocracking of paraffins.

When reforming is undertaken over the catalyst composition of the invention, the conditions employed generally include a temperature of 427 to 595°C (800 to 1100°F), preferably 482 to 566°C (900 to 1050°F); a pressure of 100 - 3550 kPa (1 atmosphere to 500 psig), preferably from 300 to 1825 kPa (30 psig to 250 psig); an inlet H ₂ /hydrocarbon of 20 or less, even zero as discussed in the Examples (because of hydrogen production during reforming, there will be a hydrogen partial pressure in the unit); and an LHSV

(liquid hourly space velocity) of 0.1 to 20, preferably 0.1 to 10. The feedstock reformed by the catalyst composition of the invention can be a straight-run thermal or catalytically cracked naphtha, conveniently having a boiling range of 65 to 205°C (150 to 400°F) so as to contain nCg+ paraffins. Preferably, the feedstock is a light naphtha fraction boiling at 80 to 120°C (180 to 250°F) so as to contain nCg - C paraffins. Because of competing isomerization and hydrocracking reactions, such light naphtha fractions are difficult to convert selectively to aromatics over conventional reforming catalyst. Prior to reforming, the naptha feedstock may be hydrotreated in conventional manner to reduce sulfur and/or nitrogen contaminant.

The naphtha feedstock may also cofed with a non-hydrogen diluent which is inert to aromatization under the reforming conditions and which thereby reduces the hydrogen partial pressure in the reforming reactor. Suitable diluents include helium, nitrogen, carbon dioxide, and light hydrocarbons through C- such

as methane , ethane , propane , butane , pentane , ethylene , propylene, butenes , pentenes and mixtures thereof. The use of C, - Cς hydrocarbons as cofeeds may be particularly desirable in that they can be easily separated from the hydrogen produced in the aromatization reactions . The diluent may also be recycle of part or all of the aromatic rich reformate . Accordingly, the diluents can constitute aromatic compounds . The diluent to hydrocarbon feed molar ratio can range from 1 to 20 with best results being obtained in the range of 2 : 1 to 10: 1 .

Post-reforming

Reformates having a research octane of 50 - 90 , preferably 70 - 90 , and containing significant quantities of C, and C_ paraffins , such as are produced by many conventional reforming processes , are conveniently upgraded by contacting with the catalyst composition of the invention. Such post-reforming is found to increase the research octane and aromatics content to the reformate. Conditions for post-reforming are conveniently the same as those described above for the reforming process of the invention .

Production of Eenzene and/or Toluene

The catalyst composition of the invention , particularly where the crystalline material is an intermediate pore zeolite , preferably ZSM-5 , can be used to convert normal hexane and/ or normal heptane to benzene and/ or toluene. Suitable conditions for this process are:

Temperature WHSV (Cfi-Cy) Total Pressure

Broad 400° to 600°C 0.1 to 10.0 5 to 500 psia (30-3450 kPa)

Preferred 450° to 550°C 0.3 to 2.5 15 to 150 psia (100-1030 kPa)

The n-hexane and/ or n-heptane feed should be substantially "isomer-free", that is in the case n-hexane , the feed should be free

of 2 and 3-methylpentane and 2,2 and 2,3-dimethylbutane. Similarly the feed should be substantially free of cyclic compounds, such as methyl cyclopentane, since the presence of significant quantities of these materials is found to increase catalyst aging. Substantially isomer-free normal hexane or normal heptane is obtainable from a distillation cut of natural gasoline. Suitable methods for separating the normal paraffins include superfractionation, urea adduction, and bulk separation by Type 5A molecular sieve. The preferred method is molecular sieve separation. Several such processes are in commercial use for the recovery of normal paraffins from refinery streams. During the adsorption step of such separation, the effluent contains isoparaffins and cyclic hydrocarbons. High purity normal paraffins are recovered by desorption or by displacement with a lighter normal paraffins such as propane. For purposes of the present invention, not more than 5 weight %, and preferably not more than 2.5 weight %, of isoparaffins and cyclic compounds should be present in the feed. The normal hexane, heptane or mixture thereof should constitute at least 90 weight % of the total Cr* hydrocarbons in the feed, and preferably 95 weight %.

In one embodiment of this invention, the normal hexane, heptane or mixture thereof is recovered by Type 5A molecular sieve separation using propane as desorbent, and the desorbed effluent containing propane is catalytically converted without prior separation of propane. Reduction of the partial pressure of the benzene and/or toluene product by propane favors its formation. Thus, in addition to the normal paraffins, the feed may contain a diluent such as hydrogen, an inert gas such as nitrogen, or an aliphatic hydrocarbon containing less than five carbon atoms. Although the conversion takes place with high selectivity and slow catalyst aging even in the absence of added hydrogen, the presence of a small amount of hydrogen may be used to further reduce aging. When hydrogen is used, it is preferred that it be used in conjunction with an inert gas or diluent described above.

Production of Styrene

The catalyst composition of the invention can also be used to convert n-octane to styrene , conveniently at a temperature of at least 500°C in the presence of an inert gas diluent such as introgen ,

Dehydrogenation of Hydrocarbons Containing ^~ 2~ ~~ Aliphatic

Moities

C ₂ ~Cr hydrocarbons or moities can be dehydrogenated to produce their unsaturated analogues using the catalyst-composition of the invention. Thus one suitable class of reactants includes alkanes of 2 to 5 carbon atoms including ethane, propane , butane, isobutane , pentane and 2-methylbutane. On dehydrogenation , these will yield ethylene, propylene, butene, isobutene, pentene and isopentene , respectively. Another class of reactants includes olefins of 2 to 5 carbon atoms such as ethylene, butene, pentene, and isopentene. Dehydrogenation of ethylene will produce acetylene; dehydrogenation of butene will produce butadiene and dehydrogenation of methyl butene will produce isoprene .

A further class of reactants includes aryl and aklylaryl substituted alphatics . Preferably , the alkyl group of the alkylaryl substituted aliphatic contains 1 - 4 carbon atoms . The aryl substituted aliphatic reactants embrace unsubstituted arylaliphatics and alkyl subtituted aryl aliphatics and; similarly, each of the alkyls of said alkyl substituted alkylaryls contains preferably less than 4 carbon atoms . By way of illustration reactants such as ethylbenzene , diethylbenzene , ethyl toluene , and cu ene are representative of these compounds . On dehydrogenation , ethyl benzene will produce styrene; p-ethyl toluene will produce p-methylstyrene; cumene, isopropenylbenzene; and diethylbenzene, divinylbenzene. In accordance with the invention , catalytic dehydrogenation conditions include a pressure of 10 to 3550 kPa (0.1 atmosphere to 500 psig) , a temperature of 300°C to 700°C, preferably 300°C* to

600 °C and most preferably from 400°C to 600°C, a reactor inlet H ₂ /feed ratios of 5 or less (even at reactor inlet ratios of zero (0) , there will be a hydrogen partial pressure in the reactor because hydrogen is a bi-product of dehydrogenation) ; and a liquid hourly space velocity of 0.1 to 50 , preferably 0 .5 to 10.

Dewaxing

The catalyst composition of the invention may also be employed to dewax hydrocarbon feedstocks containing C,.. paraffins, whereby the latter are converted to distillate range products so that the pour point and wax content of the feed is reduced. Typical waxy feedstocks which can be treated includes those boiling in the range 180 to 550°C (350 to 1025°F) and having a pour point greater than -1°C (+30°F), such as gas oils, kerosenes, vacuum gas oils, whole crudes and oils derived from tar sands, shale and coal.

Typical dewaxing conditions are listed below:

Pressure, broad 0 - 100 psig (100 - 700 kPa)

Pressure, preferred 20 - 500 psig (240 - 3550 kPa) Temperature, broad 500 - 1200°F (260 - 650°C)

Temperature, preferred 800 - 1050°F (430 - 565°C)

WHSV 0.1 - 20

WHSV, preferred 0.2 - 10

H ₂ :oil 0 - 20 : 1

The invention will now be more particularly described with reference to the following Examples and the accompanying drawings , in which:

Figure 1 is an X-ray diffraction pattern of In- ZSM-5 produced in Run No . 8 of Example 1 .

Figure 2 is an X-ray diffraction pattern of In- ZSM-12 produced in Run No . 13 of Example 1.

Figure 3 is an X-ray diffraction pattern of In- ZSM-48 produced in Run No . 6 of Example 1.

Figure 4 is a graph plotting Cr+ yield in weight % against C _r + RON value for reforming according to Example 19 compared to reforming using a conventional chloride Pt/Al ₂ 0-τ catalyst;

Figure 5 is a graph plotting gas chromatographic anaylsis of benzene and toluene (GC area % ) against hours on stream during naphtha reforming for the Pt/Sn ZSM-5 catalyst of Example 34;

EXAMPLES

Example 1

Crystalline silicate products were produced containing indium and exhibiting characteristic X-ray diffraction patterns of structures corresponding to ZSM-5 , ZSM-11 , ZSM-12, ZSM-23 , ZSM-48 and ZSM-50. Table 1 compiles the composition ranges employed in the synthesis of these products . It is to be noted that the products were .synthesized from reaction mixtures containing no del iberately added sources of Al-,0.7.

TABLE 1

a — Silica source is tetraethylorthosilicate (Et4Siθ4) b — Silica source is SPEX Industries precipitated Si0 ₂ c — R=TPA+ (tetrapropylammonium cation) d — Silica source is DeGussa fumed iθ2 e-R=(CH3 3N ^< - CH2) ₆ N ⁺ (CH3)3 f — R=TBA+ (tetrabutylammonium cation) g— R=(GH ₃ ) ₂ N^ ^((Η ₂ ) ₃ < ~ ,N ⁺ (CH3) ₂ h — Q-brand sodium silicate i — Silica source is kieselsaure precipitated Si0 ₂ j-R=(CH ₃ )3 ^(012)7^ 013)3

K — R=Dibenzyldimethylammonium ion

Table 2 is a compilation of chemical analyses of some of the indium- containing products. These products vrry in indium content from 0.36-5.20 wt% In. The formulas of the zeolite products are expressed in Table 2 as a ratio of oxides per mole of In ₂ θ3. It will be noted that the Si0 ₇ /Al ₂ θ mole ratio of each product exceeded 490 and, except for Run 14, always exceeded 1000.

00

—*, 00 rr

00

O

X-ray powder diffraction patterns of typical In-containing * zeolite products are illustrated in Figures 1 - 3. Figure 1 is the diffraction pattern for In/ZSM-5 (Sample of Run No. 8), Figure 2 is the diffraction pattern for In/ZSM-12 (Sample from Run No. 13) and 5 Figure 3 is the pattern for In/ZSM-48 (Sample from Run No. 6).

EXAMPLE 2

The In/ZSM-5 of run No. 12 was prepared as follows:

A commercial silica gel (SPEX Ind.) with very low aluminum 0 contamination was employed in the synthesis of In-ZSM-5. First,

0.85 g In(N0 ₃ ) ₃ and 2.66 g NaOH pellets were dissolved in 180.2 g de-ionized water, then 5.64 g tetrapropyl ammonium bromide (TPAEr) was dissolved in this basic solution. This solution was transferred to a 300 ml stainless steel autoclave, and 15.0 g of silica gel 5 (SPEX) was added. The autoclave was then sealed and stirring and heating was begun. The hydrogel formed by this reaction mixture is described by the following mole ratios: Si0 ₂ /In ₂ 0 ₃ 150

H ₂ 0/Si0 ₂ 48 0

The hydrogel was reacted at 160°C for 2 days at a stirring 5 rate of 400 rpm before quenching. The resultant crystalline product was filtered, washed, and dried. X-ray powder diffraction analysis showed the product to be 100% crystalline ZSM-5, when compared to the diffraction pattern of a conventional ZSM-5. Elemental analysis of the ZSM-5 product gave: C=7.93%, N=0.74%, Na=0.56%, In=2.26%, O Al 0.005%, Si0 ₂ =83.85%, Ash=88.05%, all by weight.

These results expressed in mole ratios were: C/N=12.5; Moles/ mole ln ₂ 0 ₃ : N ₂ 0=2.68, Na ₂ 0=1.23, A1 ₂ 0 ₃ = .009, Si0 ₂ =142.

Platinum incorporation was undertaken as follows: The as -synthesized zeolite was heated in nitrogen to 520°C at IC/min and held there for 6 hours . It was then calcined in air in a similar manner . The calcined zeolite analyzed for 41.05% Si , 2.21% In (Si/In2 = 152) , and 120 ppm Al , and sorbed 10.4% n-hexane at 90°C.

The calcined zeolite (3 g) was stirred in a solution of 150 mg Pt(NH ₃ ) ₄ Cl ₂ in 100 ml water at room temperature overnight. After being washed, filtered and dried, the ion-exchanged zeolite was found to contain 0.41 meq NH ₃ /g ash , which is equivalent to 1 .89% Pt on sample. The platinum tetramine zeolite was then calcined by heating in oxygen to 350°C at 0.5C/min and held there for 1 hour. Elemental analysis indicated the presence of 1.85% Pt on the final catalyst.

At very high hexane conversions ( 99%) , benzene was formed in over 94% yield. Similarly, n-heptane yielded 96% toluene.

Consistent with the non-acidic nature of this platinum catalyst, n-octane yielded predominantly ethylbenzene and ortho-xylene , 2 -methylheptane produced mostly meta-xylene, and 3 -methylheptane formed mainly ethylbenzene, para- , and ortho-xylene .

Fxample 5

In EXAMPLE 1 , indium-modified zeolties were synthysized by incorporating In(N0 ₃ ) ₃ in the crystallization reaction mixture. In the Example below, indium was incorporated post-synthesis . A high silica/alumina (10 ,000: 1 molar ratio) ZSM-11 was calcined in nitrogen and then in air at 538°C . ^~~ ^- ^' -- vapor was passed over the zeolite in a stream of nitrogen, while it was heated to 500°C at 10°C/min . The zeolite was maintained at 500°C for 1.5 hours . After cooling, the catalyst was added to 200 ml 1M NH4CI adjusted to pH 9 .5 with NH4OH. The mixture was stirred for 20 minutes at room temperature, and then filtered. The zeolite was then reexchanged for 3 hours with 1M NH4CI adjusted to pH 7.6 . Thermo gravimetric analysis indicated the presence of 0.325 meq/g ammonium ion in the zeolite .

Platinum was incorporated by ion exchange with Pt(NH ₃ )4Cl ₂ at room temperature. The platinum zeolite was then calcined in oxygen to 350°C at 0.5°C/min.

Under aromatization conditions, the catalyst effected 5 aromatization of n-heptane to toluene in high yield. At about 500°C

(up to about 538 °C) and 30 torr (4 kPa) heptane in nitrogen, toluene was formed in 94% selectivity at a conversion level of greater than 90%.

0 Example 4

Borosilicate ZSM-5 was synthesized at 170°C from a mixture of 12.4 g high purity silica (SPEX), 105 g 20% TEA hydroxide, .and 0.8 g boric acid. The as- synthesized zeolite was then calcined in nitrogen and then in air at 520°C. The calcined zeolite contained 5 41.39% Si, 0.015% Al , and 0.44% B.

Two grams of the calcined borosilicate was impregnated with

135 mg In(N0 ₃ ) ₃ , and calcined in air at 500°C for 2 hours. 1.8 g of this material was then ion-exchanged with 28 g Pt(NH ₃ ) ₄ Cl ₂ in 100 ml water at room temperature. TGA analysis 0 in hydrogen indicated the presence of 0.18 eq N/g equivalent to

0.87% Pt. The platinum-exchanged zeolite was then calcined in oxygen to 350°C at 0.5°C/min.

The catalyst activity of the foregoing composition was examined. The "non-acidic" nature of the catalyst was confirmed by 5 its ability to aromatize n-heptane to toluene in high yield. At

500 °C and 30 torr (4 kPa) heptane in nitrogen, toluene was formed in 95% yield. Furthermore, the small amounts of both methane and propane produced were exceeded by the ethane formed, indicative of the low hydrogenolysis and acid activity of the catalyst. ^* 0 % Conversion % Cl % C2 % Benzene % Toluene (Selectivity)

96 0.4 0.6 1.3 92 (96%)

99 0.5 1.0 1.5 95 (96%)

Example 5

Indium-containing zeolite ZSM-20 was synthesized by the following procedure:

12.75 grams of sodium aluminate (NaAlO ) and 6 .02 grams indium nitrate were dissolved in 57 .96 grams of deionized water, and 484.1 ml of 2.88 _N tetraethyl ammonium hydroxide (TEAOH) was added to the solution. The resulting solution was then stirred into 312.5 grams of tetraethylorthosilicate, whereafter stirring was continued for one hour until the hydrolysis reaction was complete. The resulting hydrogel was transferred to a one-liter polypropylene bottle.

The polypropylene bottle was loosely capped and placed in a steambox (100°C) to promote the crystallization of the zeolite. The next morning the bottle was removed from the steambox and the bottle cap was closed tightly. The bottle was shaken .vigorously, then replaced in the steambox. The reaction mixture for the initial hydrogel formed for the synthesis of the indium-containing ZSM-20 can be described by the following set of mole ratios : Si0 ₂ /In ₂ 0 ₃ 150

H ₂ 0/Si0 ₂ 10 0H ^' /Si0 ₂ 0.9

Na ⁺ /Si0 ₂ 0.09

TEA ⁺ /Si0 ₂ 0.93

Si0 ₂ /Al ₂ 0 ₃ 30

Samples of the solid product were removed daily from the polypropylene bottle for X-ray diffraction (XRD) analysis to determine the product crystallinity. XRD analysis showed that the ZSM-20 crystallization was complete in 14 days . The polypropylene bottle was removed from the steambox, and the solid product was filtered on a Eϋchner funnel . After filtration, the product zeolite was boiled in de-ionized water and again filtered and dried under an infrared heat lamp. After drying , a sample of the product was

submitted for XRD and chemical analysis . XRD analys is showed the product to be zeolite ZSM-20. The chemical analysis for the indium-containing ZSM-20 was:

Wei ht Percent

Si0 ₂

72.7

Indium-containing zeolite Beta was synthesized in the following manner:

5 .95 grams of sodium aluminate and 4.68 grams of indium nitrate were dissolved in 85 .14 grams of de-ionized water. After the salts dissolved, 105 .0 ml of 3.1 _N TEAOH was added to the solution. The resulting solution was transferred to a 300ml stainless-steel autoclave.

Now 46.67 grams of solid silica gel (SPEX Industries ) was poured into the autoclave , the autoclave was sealed and stirring and heating begun immediately. The reaction was carried out at 160°C with stirring (400 rpm) . The initial reaction mixture for the synthesis of indium-containing zeolite Eeta can be described by the mole ratios: Si0 ₂ /In ₂ 0 ₃ 90

H ₂ 0/SiC ₂ 12

0H ^' /Si0 ₂ 0.40 Na ⁺ /Si0 ₂ 0.09

TEA ⁺ /Si0 ₂ 0.46

Si0 ₂ /Al ₂ 0 ₃ 30

After 4 days the autoclave was quenched in a water plus ice bath to terminate the reaction. The solid product was filtered, boiled in water and again filtered. XRD analysis showed the crystalline product to be zeolite Eeta. Chemical analysis of the indium-containing zeolite Beta product gave the following results:

Weight Percent

Indium-containing crystalline aluminophosphate molecular sieve ALP0-5 was synthesized as follows:

23.1 grams of concentrated phosphoric acid (86.3% E PO4 ) was diluted with 30 .0 grams of de-ionized water. Now 10.0 grams of Kaiser alumina was stirred into this acid solution and the mixture was digested for 45 minutes at 90 °C with continuous stirring. After the digestion period a solution containing 1.18 grams of indium nitrate dissolved in 41 .0 grams of de-ionized water was stirred into the gel . Finally, 37.0 grams of 40% wt. TEAOH solution was stirred into the gel and stirring continued until a uniform gel was produced. This gel was now transferred to a 300 ml stainless- steel autoclave. The resulting reaction mixture hydrogel can be described by the following mole ratios :

P ₂ 0 ₅ /A1 ₂ 0 ₃ 1 .0 H ₂ 0/A1 ₂ 0 ₃ 59 H /A1 ₂ 0 ₃ 7.2 In ₂ C ₃ /Al ₂ 0 ₃ 0.02 TEA /A1 ₂ C ₃ 1.0

The autoclave was sealed and heated and stirring begun immediately. The reaction was carried out at 160° with stirring (400 rpm).

After 4 days the autoclave was quenched in a water + ice 5 bath to terminate the crystallization. The solid product was filtered, boiled in water and filtered again. After drying the product, XRD analysis showed the material to be crystalline aluminophosphate designated as ALPO-S. Chemical analysis gave:

0 Weight Percent

5 ~3

0 Indium-containing crystalline sil icoaluminophosphate molecular sieve SAPO-5 was synthes ized in a manner analogous to EXAMPLE 7 :

46.2 grams of concentrated phosphoric acid (86.3% H-,Pθ4 ) was first diluted with 60 .0 grams of de-ionized water 5 then 20.0 grams of Kaiser alumina was added to the solution . This mixture was now digested on a hot plate at 90°C for 45 minutes , with continuous stirring. At the end of the digestion period, a solution containing 2.36 grams of indium nitrate dissolved in 82.0 grams of de-ionized water was stirred into the gel . Next 74.0 grams of 40% ⁽ 3 wt TEAOH solution was stirred into the gel . This mixture was now stirred at room temperature until a uniform hydrogel was produced . The resulting hydrogel was transferred to a one-liter stainless-steel autoclave. Before sealing the autoclave, 2.04 grams

of tetraethylorthosilicate was transferred to the autoclave. The autoclave was then sealed and heating and stirring was begun immediately. The resulting reaction mixture can be described by the following mole ratios:

The crystallization of the indium-containing SAPO was carried out at 150°C with stirring (400 rpm) . At the end of 4 days the autoclave was quenched in a water

+ ice bath to terminate the crystallization. The ^" solid product, was filtered, boiled in water, and re-filtered . After drying under a heat lamp, XRD analysis showed that the product corresponded to silicoaluminophosphate SAPO-5. Chemical analysis gave:

12.3 3.39 1 .65 50 .8 46 .1 3.7

EXAMPLE 9

Platinum incorporation into an indium-containing silicate of ZSM-5 structure was carried out by direct addition of a platinum compound to the zeolite synthesis reaction mixture as follows:

A solution was prepared by dissolving 2.00 grams of indium nitrate and 13.07 grams of NaOH pellets in 710.28 grams of de-ionized water. After the solids dissolved , 26 .6 grams of tetrapropyl ammonium bromide (TPAEr) was dissolved in the solution . Finally 1 .29 grams of platinum tetraaminenitrate

[Pt(NH ₃ ) ₄ (N0 ₃ ) ₂ ] was dissolved in the solution , and the solution was transferred to a one-liter stainless- steel autoclave. Before sealing the autoclave , 66 .67 grams of commercial s ilica gel (SPEX Industries ) was poured into the autoclave. The autoclave was then sealed and heating and stirring was begun immediately. The reaction mixture hydrogel can be described by the following mole ratios:

Si0 ₂ /In ₂ C ₃ 300 H ₂ 0/Si0 ₂ 40

0H ^" /Si0 0.30

Na ⁺ /Si0 ₂ 0.33

TPA ⁺ /Si0 ₂ 0.10

Si0 ₂ /Pt 300

The crystallization was carried out at 170°C with stirring (400 rpm) .

After 4 days the autoclave was quenched in a water + ice bath to terminate the crystallization . The solid product was filtered , boiled in water , and finally filtered again before drying under a heat lamp. XRD analysis of the solid product showed the material to be crystalline zeolite ZSM-5 .

Chemical analysis of the indium-containing ZSM-5 product gave:

which σave:

Moles C

M oolleess NN NN ₂₂ 00 : NNaa ₂₂ 00 : AA11 ₂₂ 00, ₃ : Si0 ₂ : Pt 13.1 5 .52 5 .90 0.05 288 0 .55

Example 10

Boron-containing zeolite beta was synthesized and then calcined to remove the organic template , by heating first in N ₂ to 530°C at I0°C/min and held for 6 hrs . , then in air in N to 530°C at 10°C/min. and held for 6 hours . 25g of the calcined zeolite was ion-exchanged with 750 mg

Pt(NH ₃ )4 Cl ₂ in 400 ml H-,0 at room temperature overnight. The dried material was then heated in flowing oxygen (100 cc/min . ) to 350 °C at l/2 °C/min. and held for 1 hour.

10 of the calcined Pt-containing zeolite was then treated with 0 .9g In(N0 ₃ ) ₃ H ₂ 0 in 200 ml H ₂ 0 at room temperature overni ght .

The zeolite was filtered and washed .

The In-containing Pt/zeolite was added to 150ml H ₂ 0 and titrated to pH 9 .0 with 0.5M CsOH. The material was filtered, washed, and dried. The final product contained 0 .76% Pt, 11% Cs ,

1.1% In, and 0 .08% B.

Example 11

The synthesis of a binary oxide zeolite having the structure of ZSM-5 was carried out in the two-phase system. The aqueous phase of the two-phase system comprised 2.8 g In(N0 ₃ ) ₃ xH ₂ 0 dissolved in 35 g water to which was added 63 g TPAOH (40% in H ₂ 0) . Constituting the organic phase was 77.0 g Si (0CH ₃ )4 dissolved in 35 g of 1-hexanol . The mixture was nucleated at 180°C for 24 hours and crystallized at 200°C for 144 hours . The final product was filtered and washed. The X-ray diffraction pattern of the dried material proved it to be well-crystallized ZSM-5 .

The sample was ammoniu -exchanged (1 V NH.C1 , twice, 60 °C, 20 ml/g zeolite) and calcined . The chemical composition of the ash of a 1000°C calcined sample was 79.3 wt. % Si0 ₂ and 1.5 wt . % ln ₂ 0-τ . The ash residue also contained a small quantity, i .e. 85 ppm , of aluminum.

Temperature-programmed desorption of ammonia indicated an exchange capacity of 0.09 meq/g for the product of this example. The Si/In ratio from TPAD was 190 .5. The sample had an Alpha Value of 1 .0.

Example 12

The synthesis of Example 11 was repeated, except that the mixture contained 3.6 g In(N0 ₃ ) ₃ .xH ₂ 0 in the aqueous phase. The product material was filtered and dried . It had the same characteristic ZSM-5 X-ray lines as the product of Example 11. The material was calcined and ammonium-exchanged as described in Example 11 . The chemical composition of the ash of a 1000°C calcined sample was 78.2 wt . % Si0 ₂ and 3.1 wt . % ln ₂ 0 ₃ . The ash residue also contained a small quantity, i .e. 180 ppm, of aluminum. Temperature-programmed desorption of ammonia indicated an exchange capacity of 0.21 meq/g for the product of this example .

The Si/In ratio from TPAD was 77 .9. The sample had an Alpha Value of 2.5 .

Examples 13-17

The synthesis of Example 11 was repeated , except that the mixtures contained varying amounts of In(N0 ₃ ) ₃ .xH ₂ C. Five preparations were made , with the following compositions: Example 13 14 15 16 17 Aqueous Phase (g)

H H ₂₂ 00 40.0 40.0 35 .0 40.0 40.0 In(N0 ₃ ) ₃ xH ₂ 0 0.9 7 .2 1 .8 1.8 3.6

TPAOH, 40% 63.0 63.0 63.0 63.0 63.0

Organic Phase(g)

1-Hexanol

Si(OCH ₃ ) ₄

The product materials were filtered and dried. They had the same characteristic X-ray lines as ZSM-5. The materials were calcined and ammonium-exchanged as in Example 11. Their properties were as follows :

Example 13 14 15 16 17

Si/In (from TPAD) 193 99 95 138 77

Alpha Value 1.5 1.6 1.0 1.0 not determined Example 18

A hydrotreated Arab straight-run (LSR) naphtha was reformed over an indium containing ZSM-5 catlyst comprising 2.3 weight percent platinum, 2.88 weight percent indium, 0.45% sodium and less than 360 ppmw aluminum, with the remaining being silica. The Arab light LSR naphtha used was a C ₆ -210°F (99°C) fraction , containing 42.5 % wt C ₆ paraffins , 32.9 % wt C- paraffins , and an RON+O of 51 (calculated) . Additional properties and compositional details are described in the following table:

FEED PROPERTIES ARAB LIGHT LSR NAPHTHA

Composition, %wt. C- paraffins 3.3

Cg paraffins 1.4 C^ naphthenes 7.4 C^ aromatic 2.1

Cj paraffins 2.3 C naphthenes 7.1

C aromatic 3.1 C ₈ + PNA 3.3

Reforming of the Arab Light LSR naphtha over the platinum-indium ZSM-5 catlyst was conducted at 540°C (1000°F), 446 kPa (50 psig), 1.0 LHSV, and 5:1 H ₂ /HC mole ratio at the reactor inlet. Under these conditions reforming resulted in 84.9% wt. yield of C _r + gasoline at 93.6 RON+O. The C _r + gasoline contained 56.8% wt aromatics.

Example 19

Under the same reaction conditions as in Example 18 above, but in the absence of added hydrogen, the RON+O of the C _r + gasoline increased to 101.8, while the yield remained nearly constant at 84.18% wt. The aromatic content of the Cr+ gasoline increased to 72.9% wt. It should be noted that no change in performance of the ZSM-5 catalyst was observed in the absence of

added hydrogen from 137 to 192 hours on stream at 540 °C (1000 °F) , 446 kPa (50 psig) and 1.0 LHSV while achieving an average 101 RON+O Cr+ gasoline in 83.5 % wt yield. Data concerning catalyst stability are set forth below:

Catalyst Stability

Time on Stream, hours C ₅ + Gasoline Yield, %wt. Cr+ Gasoline Yield, %vol

Octane, RON+O 100 .0 101.8

H ₂ produced , SCF/E (Nm ³ /n ³ ) 1980( 352) 1990(354)

The results of Examples 18 and 19 constitute significant yield and octane advantages when compared with the results expected for processing the LSR naphtha in a conventional semi -regenerative reformer , using a chlorided platinum/ alumina catalyst. Typically, conventional reforming of this naphtha would result in 61% wt yield of 93 RON+O C ₅ + gasoline at reaction conditions of 540°C (1000°F) , 1724 kPa (250 psig) , 1 .0 LHSV and 10 : 1 H ₂ /HC mole ratio , with the Cς+ gasoline product containing only 51.2% wt aromatics . Additional details for comparison are set forth in Table 3 below:

Tabl e 3

Reducing the reaction pressure and hydrogen circulation would also improve the selectivity of the conventional reforming catalyst , but would result in unacceptably high aging rates . The ability of the platinum containing indium ZSM-5 catalyst to operate in -the absence of added hydrogen appears to offer significant advantages , when compared not only to semi -re generative , but also cyclic reforming processes using conventional catalysts .

Figure 4 illustrates the yield vs RON curve obtained us ing the reforming process of Example 19 as compared with the conventional chlorided Pt/A1 ₂ 0 catalyst .

Example 20

Example 18 was repeated but with hydrogen partial pressure in the reactor being reduced by the addition of a helium diluent . The data given below compares the results of Examples 18 - 20.

Example 18 Example 19 Example 20

Inlet Gas/HC Feed mole ratio

Hydrogen , %wt .

CI-C4

C5+ Gasol ine

C ₅ + RON+O

Aroma tics , %wt

It will be seen that introducing an inert carrier, in this example helium, to reduce the partial pressure of hydrogen in the reactor results in additional yield and octane gains by further improving aromatics seletivity. Hydrogenolysis and cracking reactions which result in ^~ -Γ ^~ _Λ make are suppressed. Both hydrogen yield and purity increase as a result.

Example 21

In this example the pretreated light paraffinic naphtha used in the preceding Example was processed over a silica-bound

Pt/In ZSM-5 catalyst while cofeeding hydrogen and propane. A second experiment using hydrogen only as a cofeed with the naphtha is shown for comparison. Reaction conditions were 540°C (1000°F) , 446 kPa (50 psig) and 1 .0 LHSV on naphtha feed , with 12: 1 hydrogen or hydrogen* ropane to naphtha mole ratio at the reactor inlet. The naphtha partial pressure (4 psi or 28 kPa) was therefor the same in both experiments , while the hydrogen partial pressure was lowered from 317 kPa (46 psi) to 83 kPa (12 psi ) by cofeeding propane as the diluent.

LOW PRESSURE REFORMING WITH PROPANF COFEED

Feed H ₂ Only H ₂ + C3

H ₂ /C ₅ + HC Mole Ratio — 12: 1 3: 1

C ₃ /C ₅ + HC Mole Ratio -- — 9: 1

C ₃ vol . % on naphtha 577.0 11.1 546.0

C ₃ = Yield, vol . % . — 0.7 33.0

C ₅ + Gasoline Yield, vol .% 100 .0 75.3 81.0

C ₅ + Gasoline Octane RUN+O 51 83 91

Hydrogen Produced, SCF/B (Nn ³ /m ³ ) — 580 (103) 1954 (348) Hydrogen Purity, mole % — 79 .0 96 .9

Aromatics , wt.% 5 .2 29.4 44.9

Cofeeding propane to reduce the hydrogen partial pressure improves aromatization selectivity and results in both increased gasoline yield and higher (calculated) octane. Dehydrogenation of the propane cofeed to propylene and hydrogen approaches 5 thermodynamic equilibrium at the reaction conditions chosen. There is significant increase in the hydrogen purity (defined as moles hydrogen relative to total moles hydrogen, methane and ethane), and the quantity of hydrogen produced. Note that the propane diluent and higher hydrocarbons are easily separated from the hydrogen 10 produced, thereby ensuring economical recovery of the high purity hydrogen.

The catalyst-used in this experiment was prepared by extruding an as-synthesized TPANa (In)ZSM-5 50/50 with silica according to the method of US 4,582,815. The extrudate was calcined 5 in nitrogen and then air at 538°C and then ion-exchanged with platinum tetrammine chloride solution, which was then calcined in oxygen from 25 to 350°C at 0.5° C/min and held at 350°C for 1 hour. The calcined catalyst which resulted contained 0.48 wt.% platinum, 0.49 wt.% indium, 0.11 wt.% aluminum, and 0.12 wt.% sodium. 0

Example 22

Post-processing of a reformate of 70 RON+O over a platinum indium silicate having an x-ray diffraction pattern of ZSM-5 was undertaken. 5 The reformate used as feed was obtained by sampling the second reactor of a three reactor reforming process in which the reforming catalyst was a conventional chlorided platinum catalyst. The paraffins which would have been converted in the third reactor remained, resulting in the relatively low octane number. This ^* 0 reformate was characterized by a research octane number of 67.7, a combined hydrogen content of 13.75%, and contained 2.7 %wt. C _r paraffins, 52.4 %wt. C^+ paraffins, 10.6 %wt. naphthenes, and 33.7 %wt. aromatics.

The platinum containing indium ZSM-5 catalyst used was that employed in Example 18 after approximately 18 days on stream.

The following comparison shows the results observed when post-processing low octane reformate at 540°C (1000°F) , 446 kPa (50 psig) and 1 .0 LHSV, with either hydrogen or helium at the inlet .

POST-PROCESSING REFORMATE

From the results above, it is noted that post-processing of the low octane paraffinic reformate over the platinum containing indium ZSM-5 catalyst clearly improves the gasoline octane. Reducing the hydrogen partial pressure in the reactor by cofeeding a diluent stream improves the aromatics selectivity, and results in both higher gasoline yield and octane.

Example 23

The Pt/In-ZSM-5 of Example 2 was used to catalyse the conversion of n-octane in a nitrogen diluent to aromatics including styrene. Higher temperatures and greater dilution led to improved styrene yields as shown below:

Octane Pressure Temp °C Conversion Styene Yield

10 torr (1 .3 kPa) 450 99.3% 4.8%

" 500 95 .4% 17.9 %

" 538 98.4% 33.2%

1 torr (133Pa) 550 99.4% 64.3%

Example 24

A further sample of the Pt/InZSM-5 catalyst employed in Example 18 (40.42% Si , 2.88% In , 0.45 % Na , 358 ppm Al , and 2.3% Pt ) was used to dewax a heavy nuetral raffinate feed having a pour point of 49 °C (120 °F) . The properties of the feed are l isted in Table 4.

TABLE 4

CHARGE STOCK

H-NMR PCT

NITROGEN-CHBflLUMINESCE BASIC NITROGEN-TITN, SULFUR BY XRF, 0 .002-5 % PCT

API GRAVITY

REFRACTIVE INDEX LIQUIDS FLASH PT CLEVE OPEN CUP

KINEMATIC VISCOSITY (100°C) KINEMATIC VISCOSITY (300°F) (149°C)

AROM BY SILICA GEL PERCENT RECOVERED PERCENT RESIDUE PERCENT LOSS PERCENT N0N-AR0MATICS PERCENT AROMATICS VACUUM DIST.

Initial Eoiling Point

5 VOL PERCENT DISTILLED 10 VOL PERCENT DISTILLED 20 VOL PERCENT DISTILLED 30 VOL PERCENT DISTILLED 40 VOL PERCENT DISTILLED 50 VOL PERCENT DISTILLED

60 VOL PERCENT DISTILLED 70 VOL PERCENT DISTILLED 80 VOL PERCENT DISTILLED 90 VOL PERCENT DISTILLED 95 VOL PERCENT DISTILLED . PERCENT RECOVERED END POINT

Dewaxing was carried out in a continuous flow microreactor at about 538°C, 1480 kPa (200 psig) and 0.5 WHSV. The H _∑ :oil ratio was 1.9. The product yields are shown in Table 5 below:

TABLE 5

Product Yields from Dewaxing

Days on Stream = 4.8

Lube Yield (650+F) (343+°C) = 62.5 % Kerosine Yield (330-650°F) (166-343 °C) = 14.5 % Naphtha Yield (125-330°F) (52-166 °C) = 19 .0%

Total Liquid Yield = 96 .0%

A chroma to gram of the lube and kerosine fraction showed that the waxy paraffins had been converted from the 343+°C (650°F+) range into the distillate range. The pour point of the 343+°C (650°F+) lube material was -6°C (22°F) , as compared to the feed pour point of 49 °C (120 °F) . Furthermore , shifting the paraffinic material into the distillate range produced a high quality distillate with an estimated cetane number of 55 .

Example 25

Tin ZSM-5 silicate was synthesized in a static system at 149°C (300 °F) . 400 g 28 .5 % sodium silicate (Q-brand) was added to a solution of 60 g 50% tetramethylammonium chloride , 15 g SnCl4.5H ₂ 0 , 30 g 98% H ₂ SQ4 , and 60g tetrapropylammonium bromide in 2250 g water . The mixture was stirred and then placed in a polypropylene bottle in an autoclave for 5 days . The product was 85 % crystalline ZSM-5 and consisted of large 5-10 micron crystals . In this and following preparations the zeolitic silicates produced were characterized as having at least one crystal dimension which was at least 0 .5 microns; it analyzed for 80.4% Si0 , 0.30% A1 ₂ 0 ₃ , 3.78% Sn, 2.00% Na , 7 .70% C, and 1 .05% N.

Example 26 Another tin containing ZSM-5 sample was synthesized by dissolving 0 .69 g Sn(II)S04 in 170 g de-ionized water and then adding 3.39 g NaOH. To this was added 6 .38 g tetrapropylammonium

bro ide. The mixture was transferred to a 300 ml stainless steel autoclave and 16.0 g of a low aluminum content silica gel (SPEX Ind. ) was added with stirring. The hydrogel formed by this reaction mixture is described by the following mole ratios : Si0 ₂ /Sn : H ₂ 0/Sn : 0H-/Si0 ₂ : Na+/Si0 ₂ : TPA+/Si0 ₂

75 : 40 : 0.30 : 0.35 : 0.10

The hydrogel was reacted at 160°C for 5 days with stirring (400 rpn) before quenching. The resulting crystalline product was processed in the usual manner by filtering, washing, and drying . X-ray diffraction analys is of the product zeolite showed it to be 100% crystalline ZSM-5 . SEM indicated an average crystal size greater than 2 microns .

Example 27 A tin containing ZSM-5 sample was synthesized in a similar manner to Example 26 except that the SiO„/Sn ratio was 150 and the

Na+/Si0 ₂ was 0.31. The crystalline ZSM-5 product contained 1.36 % Sn , 0 .0025% Al , 0 .93 % Na , and 89.31% Ash .

Example 28

A tin containing ZSM-5 sample was synthesized in a similar manner to Example 26 except that the Si0 ₇ /Sn ratio was 50 , the Na+/Si0 ₂ was 0.38 , and the synthes is time was 4 days .

Example 29

A tin containing ZSM-5 sample was synthesized at a Si0 ₂ /Sn ratio of 38 , a Na+/Si0 ₂ ratio of 0.40 , and a synthes is time of 3 days.

Tin incorporation was achieved during zeol ite synthesis in Examples 25 - 19 , i .e. , tin salts were added directly to the high s ilica ZSM-5 synthesis mixture. SEM data suggests that a significant portion of the tin is located outside of the large crystals formed. Nevertheless , some tin must be inside the ZSM-5 crystals , s ince it modifies the selectivity of the platinum , which itself is intracrystalline.

Example 30

Platinum incorporation into the silicates of Examples 25-29 was undertaken. The as- synthesized tin silicates were calcined first in nitrogen and then in air at 520°C . The calcined materials were ion-exchanged with aqueous PtfNH _j ^Cl-, at room temperature; typically, 15-20 mg per gram silicate was used in a non-acidic aqueous medium. The platinum tetramine-containing silicates were then calcined in oxygen to 350°C at 0 .5 C/min.

.Elemental analysis of the tin silicate of Example 26 after platinum incorporation indicated Pt = 0 .92%, Sn = 2-7%, Na = 0 .89% . Elemental analysis of the tin silicate of Example 25 after platinum incorporation, Pt=0 .65% , Sn=3.50%, Al=0 .093% .

Elemental analysis of the tin silicate of Example 27 after platinum incorporation indicated Pt=0 .80% , Sn=1 .54%, Al=31ppm .

Example 31

A solution of 11.3g S Cl ₂ -H ₂ 0 in 100 ml methanol was formed. To that solution was added 20g of a sample of H-ZSM-5 (silica:alumina ratio of 70:1). Then 2.5 ml of an aqueous solution of H ₂ PtClg (1.3g) was also added to the solution. The mixture was allowed to stand for 4 hours. The product was decanted, washed with 10 x 100 ml 3A denatured alcohol and let stand overnight under 100 ml 3-A. [3-A refers to a dessicant by Linde] . The product was decanted, washed with 100 ml 3-A and dried in an oven at 100°C. The composition of Example 31 was acidic and thus not a part of the invention. The composition of Example 31 exhibited different properties from the non-acidic platinum tin-ZSM-5 of the invention as shown below:

Non-Acidic Acidic

Catalyst of Composition of the Invention Ex. 7

Alpha value in 424 62

He 1 hr on stream

Eenzene selectivity 50.4 2.0 from alpha value test

In the above composition, hexane was the feed and the numerical value, referred to as alpha in the foregoing table, is used as a measure of the hexane conversion activity. From the foregoing results it can be noted that the composition in accordance with the invention exhibited greater hexane conversion activity than the Example 31 composition and in the alpha value test the catalyst of the invention exhibited greater selectivity for hexane conversion to benzene.

Example 32

The ability of some of the catalysts of Example 30 to aromatize n-heptane to toluene was assessed at 538 °C and 30 torr (4 kPa) heptane in nitrogen. Heptane was introduced into the reactor in a nitrogen stream passing through a vaporizer containing heptane at 15-20°C. The presence of tin in these Pt/ZSM-5 catalysts greatly increased the toluene yield and suppressed the amount of methane formed. Some of the data obtained is shown below; scandium, titanium , and boron-containing Pt/ZSM-5 catalysts , prepared in a s imilar manner , are included for comparison purposes . Yields shown are on a hydrogen-free weight bas is .

The platinum-exchanged catalys ts of Examples 26 and 29 were used to effct reforming of a hydrotreated Arab light naphtha , boiling range 82 - 121°C (180-250°F) , at 540°C (1000°F) and atmospheric pressure (100 kPa ) in nitrogen. The results are shown below:

Pt/Sn-ZSM- Ex. 29 2.0 4

Selective conversion of the normal paraffins to aromatics was observed .

Fxample 54

^" An extended light naphtha reforming run was conducted over a 0 .9% Pt/Sn-ZSM-5 catalyst of Example 26 as shown in Figure 5. The initial inlet temperature was 527°C, and this was increased incrementally to 550°C. WHSV was 1.35 initially, and later , 1 .0. The on-line GC yields of both benzene and toluene are shown in Figure 5. Formation of ^~ _T ~ ^~ _Λ light gases was quite low: at 45 hours on stream light gas formed was about 0.6 % , and about 1 .5 % at 300 hours on stream.

Throughout the run , the liαuid product was collected in a CaCl ₂ -ice bath at approximately -40 °C. Overall liquid recovery was 90-92 weight per cent of feed. The measured research octane ratings (RON+O) of the various fractions collected ranged from 97 after 1 day on stream to better than 92 after 12 days . The aging rate was less than 1/2 an octane number per day. The liquid products contained significant amounts of olefins as indicated by their bromine numbers which ranged from 44 to 33.

The very high aromatization selectivies of these platinum/tin ZSM-5 catalysts , and their apparent stability in the absence of added hydrogen , make them ideal candidates for reforming catalysts .

Example 35

The aromatization of a hydrotreated ^~ _ζ .~ ^~ - light naphtha was investigated over a 1.6% Pt/Sn-ZSM-5 (analysis of which indicated 1.6% Pt; 3.0 Sn; 0.64 Na and less than 59 ppm A1 ₇ 0 ₃ ) in hydrogen at a H ₂ /HC ratio of 1 at atmospheric pressure and 1 WHSV. The temperature ranged from 520-538°C over a period of 14 days. Liquid products were recovered in better than 90 wt% yield based on feed. The RON'S of the collected products were 97-98.

The above run was continued at 239 kPa (20 psig) and 538-550°C. The liquid product recovered in 85 wt% yield after a total of 25 days on stream exhibited a RON of 97 and M0N (motor octane number) of 83.

Example 36

A silica-bound extrudate Pt/Sn-ZSM-5 was prepared and used for naphtha reforming. A high silica tin-containing ZSM-5 was synthesized as described earlier. It contained 6.84% C, 0.61% N, 5.31% Sn, 0.0057% Al , 1.04% Na, and 79.9% Si0 ₂ . The silica-bound extrudate, containing 35% silica binder, was prepared according to U.S. Patent No. 4,582,815. The dry extrudate was calcined in nitrogen at 540°C

(1000°F), and then ion-exchanged with Pt(NH ₃ ) ₄ Cl _? . The platinum-containing catalyst was then calcined in 0-, at 350°C. The final catalyst composition analyzed for 0.78% Pt, 3.66% Sn, 0.33% Na, and 0.23% A1 ₂ 0 ₃ . A pretreated ^~ ₍ ./ ^~ light naphtha was reforme over the above catalyst in hydrogen at a H ₂ /HC ratio of 1, at 1 WHSV, atmospheric pressure, and 538 °C. The liquid product recovered in better than 90 wt% yield has a RON clear of 95.6.

Example 37

A mixture of C^-Cg normal paraffins (25% Cg, 29% C _y , 25% C ₈ , and 20% C _g ) was reformed over a Pt/Sn-ZSM-5

(analysis of which indicated 1.5% Pt; 2.7% Sn; 0.63% Na and 72 ppm A1 ₂ 0 ₃ ) catalyst in hydrogen at a H ₂ /HC ratio of 1, at atmospheric pressure, 1 WHSV, and 538°C. The liquid product which was recovered in 84 wt% yield had a RON of 100. The Sn-ZSM-5 was prepared according to Example 26.

Example 38

A model feed consisting of a 3:1 wt. ratio of n-heptane and methylcyclopentane was reformed over a non-acidic Pt/Sn-ZSM-5 catalyst containing 1.5% Pt, 2.7% Sn, 0.63% Na, and 72 ppm

A1 ₂ 0 ₃ . Conditions were 1 WHSV, 860 kPa (110 psig), and 538 °C.

The diluent ratios used were 4:1:1 and 6:1:1 N ₂ _H ₂ :HC. It was found that when the diluent ratio was increased, the yield of aromatics (toluene) increased while the amount of residual unreacted heptane decreased. At the same time, loss to ^' -,- ^' - light hydrocarbons decreased form 6.5 wt% to ^' 4.0 wt%.

Example 39

The Pt/Sn-ZSM-5 of Example 36 was used to effect dehydrogenation of n-pentane using a down-flow glass reactor containing 1.2 g of the catalyst. Pentane was introduced into the reactor in a nitrogen stream passing through a vaporizer containing pentane at 0°C. The reaction was conducted at 538°C, 1 atmosphere (100 kPa) pressure, and 27 kPa (200 torr) pentane in nitrogen. After about 20 hours on stream, the conversion of n-pentane was 68%, with loss to C4- hydrocarbons less than 1.7%. Compositional analysis of the liquid collected over the period of 2.5 to 231 hours on stream is shown in Table 5 below:

TAELE 6 Liquid Product Composition Component

^c l ^{" c} 4 n- Pentane iso-Pentane

Pentene-1 trans-Pentene-2 cis-Pentene-2

3-Methylbutene-l

2-Methylbutene-l 2-Methylbutene-2

Cyclopentane Cyclopentene Cyclopentadiene Non- cyclic Dienes

The results suggest that dehydrogenation and dehydrocyclization compete effectively with hydrogenolys is over this catalyst , and that they also dominate over skeletal isomerization .

The measured clear RON of the recovered liquid product was 97.1 . The actual RON of the dehydrogenation products of pentane must be even higher , since the total product still contained 25% n-pentane which has a RON of 63.

Example 40

A stream of ethylbenzene (approximately 10 torr (1 .3 kPa ) ) in nitrogen was passed over a 1 .8% Pt/Sn-ZSM-5 catalyst at atmospheric pressure, 0.4 WHSV, and 538°C . On-line GC analysis indicated a styrene yield of 74 % with a selectivity of 89% .

Example 41

An aged sample of the catalyst used in Example 40 was used to study the dehydrogenation of 3 -methyl pentane at atmospheric pressure, 1 WHSV, and 538°C in a mixture of N ⁷ ₂ and H ₂ at a ratio of 4 : 1: 1 relative to hydrocarbon . At 20% conversion , selectivity to methyl pen tenes was about 65 % .

Example 42

The catalyst of Example 41 was used to study the dehydrogenation of methylcyclopentane under similar conditions except that the total pressure was 790 kPa (100 psig) . At 18 % conversion, methylcyclopentene was observed as the major product in about 45% selectivity. >

The upgrading of n-pentane via dehydrogenation to olefinic and cyclic C _r hydrocarbons over non-acidic tin-modified Pt/ZSϊ5-5 catalysts appears to offer an attractive alternative to pentane isomerization as a means of octane enhancement of this fraction, while at the same time reducing the total vapor pressure.

Whereas isomerization of n-pentane to an equilibrium mixture of isopentane and n-pentane yields a mixture having a clear RON of about 87 , dehydrogenation and dehydrocyclization produced a liquid of 97 RON, despite containing 25% n-pentane. About 10% of the product formed over Pt/Sn ZSM-5 cons isted of cyclopentyl compounds , 33% linear olefins , 13% branched olefins , and about 16 % non-cyclic dienes .

Example 45 Thallium ZSM-5 was synthesized by dissolving 0.85 g T1N0 ₃ in 170 .6g deionized water and then by adding 2.05g NaOH pellets .

After all the base had dissolved , 6 .38g tetrapropylammonium bromide

(TPABr) was added. The resulting solution was transferred to a

300ml stainless steel autoclave and 16 .0g of silica gel (SPEX Ind. ) was stirred into the solution. The hydrogel produced can be described by the following mole ratios:

Si0 ₂ /Tl ₂ 0 : H ₂ 0/Si0 ₂ : 0H-/Si0 ₂ : Na+/Si0 ₂ : TPA+/Si0 _£ 150 40 0.20 0.21 0 .10

The hydrogel was heated in the autoclave for 4 days at 160°C, with stirrin at 400rpm. The product was filtered , washed and dried. X-ray diffraction analysis indicated it to be 100 % crystalline ZSM-5 .

Ele ental analysis indicated the presence of 8.26% C, 1.88% * H, 0.74% N, 0.54% Na, 4.33% Tl , 80.65% Si0 ₂ , and 0.0095% Al in the

ZSM-5 product.

Catalyst preparation was undertaken as follows: The 5 as- synthesized thallium silicate was calcined, first in nitrogen and then in air, at 520°C. The calcined zeolite contained 2.43% Tl, 38 ppm Al, and 43.15% Si.

Platinum was incorporated by ion exchange with Pt(NH ₃ )4Cl ₂ (15 mg/g zeolite) at room temperature. TGA 10 ammonia titration in hydrogen indicated the presence of 0.67% Pt.

The platinum-containing zeolite was then heated at 0.5°C/min. in oxygen to 350°C where it was maintained for one hour.

Example 44 15. The "non-acidic" nature of the catalyst of Example 43 was confirmed by its ability to aromatize n-heptane to toluene in high yield. At 538°C and 4 kPa (30 torr) heptane in nitrogen, toluene was formed in 83-88% selectivity at a conversion of 99+%. Total yield of benzene plus toluene was greater than 90%.

20

Example 45

The catalyst of Example 43 was used to study the reforming of a hydrotreated Arab light naphtha, boiling range 82-121°C (180°-250°F). The reaction was run at 538°C at atmospheric pressure

25 at 1.8 WHSV and a N ₂ /HC ratio of 2.2. The results obtained are shown below:

C _r C ₄

Methyl pen tanes n- Hexane ,t. Methylhexanes n-Heptane Benzene Toluene

The above results indicate highly selective aromatics formation together with very low ^~ ι" ^~ ^ gas production .

Example 46 Lead-containing ZSM-5 was synthesized. A solution A was prepared by dissolving 3.31g Pb(N0 ₃ ) ₂ in 338 .8g de-ionized water. A solution B was prepared by dissolving 12.4g NaOH in 300g de-ionized water. 25.94g TPA bromide was then dissolved in solution B, which was then poured into solution A. 60 .0g silica gel (SPEX Ind. ) was placed in a 1-liter stainless steel autoclave. The solution was now transferred to the autoclave, and the mixture was stirred for two minutes before sealing the autoclave. Stirring and heating were begun immediately. The composition of the hydrogel formed is described by the following mole ratios: Si0 ₂ /Pb : H ₂ 0/Si0 ₂ : 0H ^" /Si0 ₂ : Na ⁺ /Si0 ₂ : TPA ⁺ /SiC ₂

90 : 40 : 0.30 : 0.34 : 0.10

The zeolite crystallization was carried out at 160 °C with stirring at 400 rpm for 4 days . The product ZSM-5 analyzed for 7.96% C, 0 .7% N, 0 .97% Na , 4.0% Pb , 86.48% ash, and 235 ppm A1 ₂ 0 ₃ . Platinum incorporation was effected in a manner similar to that in Example 43.