ISOPROPYL ALCHOL Summary of the Invention

This invention intends to improve stability of zeolite catalyst to use in cumene production by alkylation of benzene with isopropyl alcohol, comprising contacting zeolite catalyst with silane compound wherein the ratio of millimole of silane compound to gram of catalyst is in a range of 0.01 to 1 , in a temperature range of room temperature but not higher than boiling point of the silane compound, for 0.5 to 48 hours. The aim of the process according to this invention is to treat surface of zeolite catalyst without changing structure of the catalyst, resulting in that the catalyst is more stable to water which is by-product of the reaction, and the lifetime of catalyst is longer.

Field of the Invention

This invention relates to a chemical mixture and s chemical process, especially in the process for improving stability of zeolite catalyst to use in cumene production by alkylation of benzene with isopropyl alcohol.

Background of the Invention

It has been known that cumene or isopropylbenzene, an alkyl aromatic substance obtained from alkylation reaction of benzene, is an important precursor for phenol production. More than 90% of phenol production uses cumene as precursor. However, such phenol production usually obtains acetone as a by-product, which is cheap and has low market demand. Nevertheless, acetone has an advantage in its ability of being used as a precursor for cumene production. Therefore, reaction of acetone for converting to cumene has high commercial interest.

The production of cumene from acetone can be divided into two stages which are the hydrogenation of acetone to be isopropyl alcohol (IPA) or isopropanol, and then the alkylation of the obtained isopropyl alcohol to cumene as the following reactions.

US Patent No. 5015786 discloses cumene production by the alkylation of benzene with isopropyl alcohol using Y-zeolite as a catalyst. Cumene obtained from said reaction has a production yield of 17.7%.

US Patent No. 6512153B1 discloses cumene production by the alkylation of benzene with isopropyl alcohol using zeolite catalysts which are ZSM-5, ZSM-12, dealuminated H- mordenite, Y-zeolite, and β-zeolite. The results show that β-zeolite exhibits the highest activity of cumene selectivity of 85%,.

US Patent No. 6841704B2 discloses cumene production by the alkylation of benzene with isopropyl alcohol using β-zeolite catalyst supported on silica alumina (Si0 ₂ /Al ₂ 03) in the ratio of 70:1 to 200:1. The selectivity of cumene could be up to 93.1%.

US Patent No. 7524788B2 discloses cumene production in one step by feeding acetone, benzene and hydrogen to be reacted together. The catalysts are combined in hydrogenation and alkylation processes. The catalyst used in the alkylation reaction is β- zeolite which has cumene selectivity of 80%.

US Patent No. 7790936B2 discloses cumene production from acetone in one step. In alkylation step of benzene and isopropyl alcohol, catalyst used is β-zeolite or MCM-22. The selectivity of cumene could be up to 70 to 80%.

US Patents No. 8212096B2, WO2010014404 Al, CA2729173, and CA2729266C disclose the steps of reacting zeolite catalyst with silicone, siloxane, polysiloxane, or silane compounds for the improvement of zeolite catalyst structure for alkylation reaction of benzene or aromatic compounds in the production of alkylated aromatic compounds. However, these patents do not disclose the surface treatment or increasing of stability of zeolite catalyst.

As in alkylation step of benzene and isopropyl alcohol, apart from cumene obtained as primary product, water is also produced as by-product. Water obtained in this reaction is poison to the zeolite catalyst which deactivating catalyst and reducing the selectivity of cumene production. As a result, this invention aims to improve stability of zeolite catalyst for the production of cumene from alkylation reaction of benzene with isopropyl alcohol.

Brief Description of the Drawings

Figure 1 shows cumene selectivity comparing between modified zeolite catalyst according to this invention to the compared catalyst.

Figure 2 shows aromatic selectivity comparing between modified zeolite catalyst according to this invention to the compared catalyst.

Figure 3 shows x-ray diffraction (XRD) pattern of compared MCM-22 catalyst and modified MCM-22 catalyst according to this invention, comparing between before and after being used.

Detailed Description of the Invention

This invention discloses a process for improving stability of zeolite catalyst to use in cumene production by alkylation of benzene with isopropyl alcohol, comprising contacting zeolite catalyst with silane compound in a certain condition, making the surface of zeolite catalyst more hydrophobic without affecting its structure. Said improvement makes the catalyst more stable to water which is the by-product produced during alkylation reaction of benzene with isopropyl alcohol, and longer lifetime of the catalyst. The improving process can be explained according to the specification as the following.

Any aspect showed here aims to include every application of other aspects of this invention unless stated otherwise.

Technical terms or scientific terms used herein, have definitions as understood by those having an ordinary skill in the art, unless stated otherwise.

Equipment, apparatus, methods, or chemicals mentioned here means equipment, apparatus, processes or chemicals commonly operated or used by those skilled in the art, unless explicitly stated otherwise that they are equipment, apparatus, methods, or chemicals specifically used in this invention.

The use of the singular or plural nouns with the term "comprising" in the claims or in the specification refers to "one" and also "one or more", "at least one", and "one or more than one".

All compositions and/or processes disclosed and claimed are aimed to include aspects of the invention from actions, operation, modifications, or changing of any parameters without performing significantly different experiments from this invention, and obtaining similar objects with same utilities and results of the present invention according to persons skilled in the art although without mentions in claims specifically. Therefore, substitution or similar objects to the present invention including minor modifications or change which clearly seen to persons skilled in the art should be considered with scope, spirit, and concept of the invention as appended claims.

Throughout this application, the term "about" is used to indicate that any value presented herein may potentially vary or deviate. Such variation or deviation may result from errors of apparatus, methods used in calculation or from individual operator implementing apparatus or methods. These include variations or deviations caused by the changes of physical properties.

The following shows detailed description of the invention without any intention to limit the scope of the invention.

This invention relates to a process for improving stability of zeolite catalyst to use in cumene production by alkylation of benzene with isopropyl alcohol. Said process comprises contacting zeolite catalyst with silane compound wherein the ratio of millimole of silane compound to gram of catalyst is in a range of 0.01 to 1, in a temperature range of room temperature but not higher than boiling point of the silane compound, for 0.5 to 48 hours.

In one aspect of the invention, the ratio of millimole of silane compound to gram of catalyst is in the range of 0.01 to 1, and preferable is in the range of 0.3 to 0.5.

In one aspect of the invention, the temperature is between room temperature but not higher than boiling point of silane compound. Preferably, the temperature is from room temperature to 100 °C.

In one aspect of the invention, the contacting time for improving stability of zeolite catalyst is from 0.5 to 48 hours. Preferably, the contacting time for improving zeolite catalyst is from 20 to 24 hours.

In one aspect of the invention, the silane compound may be selected from dimethyldichlorosilane, octyltrichlorosilane, octadecyltrichlorosilane, trichloro(phenyl)silane, or a mixture thereof. Preferably, the silane compound is dimethyldichlorosilane. The zeolite catalyst that can be improved stability by the process according to this invention may be selected from, but not limited to MCM-22, MCM-36, TNU-9, ZSM-5, ZSM-12, ITQ-39, Y-zeolite, β-zeolite catalyst. Preferably, the zeolite catalyst is MCM-22.

In each step of the improving stability of catalyst described in this invention, unless being stated specifically, organic solvent may be selected from, but not limited to aromatic hydrocarbon, aliphatic hydrocarbon, cyclic hydrocarbon, normally are toluene, benzene, ethylbenzene, xylene, hexane, cyclohexane, cyclohexene, and heptane.

Said improving process of catalyst may further comprise a step of drying if necessary. Said step may be selected from, but not limited to stirring, evaporation, and vacuum drying.

In one aspect, the invention involves using of modified zeolite catalyst according to the invention in a cumene production process by alkylation of benzene with isopropyl alcohol wherein said catalyst may be used in liquid, semi-liquid, or solid form.

In one aspect, the process for producing cumene by alkylation reaction of benzene with isopropyl alcohol may be performed in reactor but not limited to fixed-bed reactor. The process can be performed in batch or continuous process.

Hereafter, examples of the invention are shown without any purpose to limit any scope of the invention.

Preparation of compared catalyst

The synthesis of compared catalyst MCM-22 started from adding 6 g of sodium hydroxide (NaOH) into about 60.5 g of distilled water. Then, gradually added 12.4 g of hexamethyleneimine (HMI) into the solution and stirred. Then, dropped 50.7 g of 30 % by weight slurry silica into prepared solution and stirred for about 15 minutes. Then, dropped obtained solution into aluminium sulphate solution containing 3.5 g of aluminium sulphate (A1 ₂ (S0 ₄ ) ₃ .18H ₂ 0) in 87.5 g of distilled water and stirred for about 30 minutes. Then, dropped about 4.5 g of concentrated sulfuric acid (96 % wt) into above solution and stirred for about 30 minutes. The obtained solution was autoclaved at 150 °C at 40 rpm for 4 days, then quenched in water. The obtained solid was filtered and washed with distilled water till neutral and dried at about 100 °C for at least 8 hours. The obtained dried powder was calcinated at about 580 °C for 5 hours. Crystal structure was confirmed by x-ray diffraction (XRD) technique. Preparation of catalyst according to the invention

The catalyst according to the invention can be prepared by contacting compared catalyst MCM-22 prepared from above process with silane compound in the following steps.

The compared catalyst MCM-22 was dispersed in toluene at a ratio about 20 mL/g of catalyst in ultrasonic bath. Then, dimethyldichlorosilane solution was added into toluene at a ratio about 0.5 mmol/g of catalyst and stirred continuously for about 24 hours. The obtained solid was filtered and washed with ethanol and then dried at the temperature of at least 100 °C.

Cumene selectivity test

The catalyst was pretreated with nitrogen gas at the flow rate of 10 mL/min at about

200 °C for 1 hour. Then, the temperature was reduced to 190 °C. Cumene selectivity of the catalyst was tested in a fixed-bed reactor fed with benzene and isopropyl alcohol (a mole ratio of benzene to isopropyl alcohol is 3:1) into a heated vessel with controlled temperature at about 70 °C before entered to the reactor which heated by vessel heater with a space velocity of 4 per hour. The catalyst was contained in the reactor. The obtained product was analyzed for its chemical composition using gas chromatography technique. The production selectivity of cumene and aromatic were calculated from the following formula.

Cumene selectivity = mol of cumene produced

mol of isopropyl alcohol used in the reaction

Aromatic compounds selectivity = mol of aromatic compounds produced mol of isopropyl alcohol used in the reaction

Figure 1 and 2 show results of cumene selectivity and aromatic selectivity of modified zeolite catalyst according to this invention comparing to the compared catalyst MCM-22. When considering the weight of cumene produced to the weight of catalyst at each times (x-axis) which means the reaction rate at each interval, it is found that the modified zeolite catalyst according to this invention gives higher production selectivity and higher stability of cumene and aromatic compounds when time passes.

Figure 3 shows crystal characteristics of compared MCM-22 catalyst and MCM-22 catalyst modified with the silane compound according to this invention. Both catalysts were compared before and after being used. The results show that the process for improving stability of zeolite catalyst according to the invention using silane compound has no effect on the structure of MCM-22 catalyst. Moreover, although modified MCM-22 catalyst according to this invention was used in alkylation reaction of benzene with isopropyl alcohol, said catalyst still remains intact as MCM-22 catalyst with no change in its structure.

Best Mode of the Invention

Best mode of the invention is as disclosed in the detailed description.