CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This Application claims the benefit of the priority of commonly-owned and co pending US Provisional Patent Appl. No. 62/647,296, filed on March 23, 2018, the disclosure of winch is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

FIELD OF TH E INVENTION

[0003] The field of this invention is hydrogenation and oligomerization processes for producing refined hydrocarbon products from olefin-containing Fischer-Tropsch reaction feedstocks.

NON-LIMITING SUMMARY OF THE INVENTION

[0004] information will now be provided that may be related to or provide context for some aspects of the techniques described herein and/or claimed below. This information is background for facilitating a better understanding of that which is disclosed herein. Such background may include a discussion of "related" art. That such art is related in no way implies that it is also "prior" art. The related art may or may not be prior art. The information provided in this section of this disclosure is to be read in this light, and not as an admission of prior art.

[0005] One utility of the Fischer-Tropseh (sometimes abbreviated here as “FT”) reaction process is in the conversion of syngas (a mixture of CO and ¾, sometimes derived from biomass) feed stock into liquid hydrocarbon fuels. Such liquid hydrocarbon fuel reaction products, however, typically comprise a mixture of aliphatic hydrocarbons of varying carbon chain lengths, with substantial quantities of low (<C ₈ ) carbon number hydrocarbons, as well as olefin content levels that often far exceed the minimum specifications (<i wt%) required for certain types of fuel, e g., jet fuel. A need therefore exists for facile methods of refining FT reaction products to produce fuels with substantial quantities of hydrocarbons in the jet fuel range (i.e., Cg-ie), with significantly minimized olefm content.

[0006] This invention addresses the aforesaid need by providing, in one aspect, a process for refining a Fischer-Tropsch reaction product having an olefm content greater than 1 wt%, based on the total weight of the Fischer-Tropsch reaction product, wherein hydrocarbon number distributions are selectively increased in the jet fuel range while olefin content is also reduced. In this aspect, the process comprises:

feeding the Fischer-Tropsch reaction product as a liquid feed into a reaction zone so as to bring the liquid feed into contact with a catalyst comprising palladium at one or more temperatures in the range of about 60° C. to about 150° C., under reaction conditions so as to form a hydrogenated reaction product; and

recovering the hydrogenated reaction product, the hydrogenated reaction product being characterized at least by a total olefin content which is lower than the total olefm content of the Fischer-Tropsch reaction product immediately prior to its introduction into the reaction zone, a C ₈ -C _l6 aggregate hydrocarbon content which is greater than a Cx-Cg, aggregate hydrocarbon content of the Fischer-Tropsch reaction product immediately prior to its introduction into the reaction zone and a C4-C7 aggregate hydrocarbon content which is less than a C ₄ -C ₇ aggregate hydrocarbon content of the Fischer-Tropsch reaction product immediately prior to its introduction into the reaction zone.

[0007] In one particular aspect of the invention, the catalyst further comprises a support, such as for example, alumina.

[0008] In a particular aspect of the invention, the amount of palladium in the catalyst is in the range of about 2 to about 8 wt%, based on the total weight of the catalyst.

[0009] In still another particular aspect of the invention, the reaction conditions comprise a pressure within the reaction zone during feeding in the range of about 100 to about 500 psig (i.e , about 790 to about 3550 kpa), and wherein the feeding of the Fischer- Tropsch reaction product is carried out while co-feeding a gas stream comprised of hydrogen gas.

[0010] In yet another particular aspect of the invention, the olefm content in the Fischer-Tropsch reaction product is greater than 15 wt%, based on the total weight of the Fischer-Tropsch reaction product. In still another aspect of the invention, the olefm content in the Fischer-Tropsch reaction product is greater than 35 wt%, based on the total weight of the Fischer-Tropsch reaction product.

[0011] In another process according to one aspect of the invention, the olefm content of the hydrogenated reaction product is less than 1 wt%, based on the total weight percent of the hydrogenated reaction product. [0012] And in yet another process according to one aspect of the invention, wherein the Fischer-Tropsch reaction product is a hybrid cobalt-zeolite catalyzed Fischer-Tropsch reaction product. That is to say that the Fischer-Tropsch reaction product was previously formed via a reaction catalyzed by a hybrid cobalt-zeolite under catalytic conditions.

[0013] These and other aspects, features and advantages of the invention will now further appreciated from the following detailed description, including the accompanying figures and claims.

BRIEF DESCRIPTION OF FIGURES

[0014] The claimed subject matter may be understood by reference to the following description taken in conjunction with the accompanying figures, in which:

[0015] FIG. 1 illustrates a bar graph of the analyzed carbon number distribution, by weight percent, of a Fischer-Tropsch reaction product feed stock sample prior to undergoing a oligomerization/hydrogenation reaction process in accordance with one aspect of the invention.

[0016] FIG. 2 illustrates a bar graph of the analyzed carbon number distribution, by weight percent, of a GC simulated distillation of an oligomerization/hydrogenation reaction product feed sample from a reaction zone in a reactor carrying out a reaction in accord with one aspect of the invention using the FT reaction product feed stock of Fig. 1.

[0017] FIG. 3 illustrates a bar graph of the analyzed carbon number distribution, by weight percent, of a GC simulated distillation of an oligomerization/hydrogenation reaction product feed sample from the reaction zone in the reactor carrying out the reaction referenced in Fig. 2.

[0018] FIG. 4 illustrates a bar graph of all of the analyzed carbon number distributions, by weight percent, of the FT reaction product feed stock sample and the oligomerization/hydrogenation reaction product feed samples from the reaction zone in the reactor carrying out the reaction referenced in Fig. 2 in accord with one aspect of the invention.

[0019] FIG. 5 is illustrates a bar graph of the overall weight of hydrocarbons in the CV Ci ₆ range for each of the FT reaction product feed stock sample and the oligomerization/hydrogenation reaction product feed samples from the reaction zone in the reactor carrying out the reaction referenced in Fig. 2 in accord with one aspect of the invention. DETAILED DESCRIPTION

[0020] Illustrative embodiments of the subject matter claimed below will now be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business- related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0021] The embodiments illustratively disclosed herein may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,”“containing,” or“including” various components or steps, the compositions and methods can also“consist essentially of’ or“consist of’ the various components and steps. Further, various ranges and/or numerical limitations may be expressly stated below. It should be recognized that unless stated otherwise, it is intended that endpoints are to be interchangeable. Further, any ranges include iterative ranges of similar magnitude falling within the expressly stated ranges or limitations disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. It is to be noted that the terms“range” and“ranging” as used herein generally refer to a value within a specified range and encompass all values within that entire specified range.

[0022] Furthermore, various modifications may be made within the scope of the disclosure as herein intended, and aspects of the invention described in this disclosure may include combinations of features other than those expressly claimed.

[0023] Various terms as used herein are shown below. To the extent a term used in a clai is not defined below, it should be given the broadest definition skilled persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing. Further, unless otherwise specified, all compounds described herein may be substituted or un-substituted and the listing of compounds includes derivatives thereof.

[0024] The FT reaction products that may serve as the feed stock of processes in accord with one aspect of the invention will typically be formed by a reaction between syngas and a FT catalyst under FT reaction conditions. The FT catalyst employed can vary, but will typically be a supported catalyst, and of this category in at least one aspect of the invention is a solid acid hydrogenation catalyst, such as for example, a zeolite (e g., ZSM-5) catalyst impregnated with cobalt (e.g., in an amount in the range of about 5 to about 15 wt% based on total weight of the catalyst). The syngas employed as feedstock to the FT reaction can be characterized generally as any gaseous mixture of carbon monoxide and hydrogen, typically with a hydrogen to carbon monoxide ratio of about 1.5 to about 2.0. The conditions employed to ca _' out the FT reaction also may vary, but will typically be carried out at temperatures in the range of about 160 to about 260 °C, and pressures in the range of about 1 atm to about 100 atm (about 101 kPa to 10,133 kPa) and a gaseous hourly space velocity less than 20,000 volumes of gas per volume of catalyst per hour. For greater details of examples of specific FT reaction catalysts of the cobalt on zeolite type, and their reactions carried out to convert syngas into FT reaction products in this manner, see for example U.S. Patent 8,377,996, the disclosure of which is incorporated herein by reference.

[0025] The resulting FT reaction product may be fed as a liquid into a reaction zone operating under relatively mild reaction conditions in accord with one aspect of the invention. The reaction zone is typically within a reactor configured to receive the FT reaction liquid product feed after removal of water and to contain a catalyst comprised of palladium. The liquid hourly space velocity (LHSV) within the reaction zone in one aspect of the invention will typically be in the range of about 0.5 to about 4 g/g catalyst/hour.

[0026] In one aspect of the invention, the catalyst will be disposed in the reactor comprised of palladium as a supported catalyst. Non-limiting examples of suitable supports include alumina, silica, carbon and the like. In one aspect of the invention, the support is gamma alumina with a surface area in the range of about 150 to about 300 m7g as measured by the standard N2-BET method. When present, the amount of palladium in a supported palladium catalyst in one aspect of the invention will be in the range of about 2 to about 8 wt.%, or about 4 to about 6 wt. %, or about 5 wt.%, based on the total weight of the catalyst. The supported palladium catalyst typically can be fabricated by impregnating the selected support with the palladium, which is typically in the form of a palladium salt in aqueous solution during the impregnation. The resulting impregnated support is then dried and calcined at one or more temperatures sufficient to decompose the salt and form the supported palladium catalyst.

[0027] The reaction zone is operated at temperatures in the range of about 60 to about 150° C. in one aspect of the invention. In another aspect, the temperature is in the range of about 75 to about 125 °C The pressure in the reaction zone typically is in the range of about 790 to about 3550 kPa in one aspect of the invention, or in the range of about 1200 to about 2500 kPa in another aspect of the invention

[0028] The FT reaction product may be co-fed into the reactor along with a co-feed of hydrogen gas. The hydrogen gas feed may further comprise nitrogen gas, typically in a minor amount (e.g., less than 10 wt.%, or about 5 wt.%, based on the total weight of the gas). Such hydrogen gas feed is typically under one or more pressures in the range of about 790 to about 3550 kPa, and may be fed at a feed gas space velocity in the range of about 100 to about 15000 scc/g catalyst/hour.

Example

[0029] To facilitate a better understanding of the disclosure, the following example illustrative of an aspect of the invention is given. Unless otherwise designated herein, all testing methods specified herein are the current methods at the time of filing. In no way should the following example be read to limit, or to define, the scope of the appended claims.

[0030] Reactor Description. The reactor was a ½ inch O.D. stainless steel tube slurry reactor loaded with an alumina-catalyst mixture characterized as follows: 0.50208 g of 5 wt. % Pd on gamma alumina catalyst diluted with 5.00 g of alpha alumina with a surface area of about 0.3 square meter per gram and commercially available from Saint-Gobain under the commercial brand Dentone® 99. A hydrogen gas co-feed into the reactor was controlled at 95 Standard Cubic Centimeters Per Minute (SCCM, using a temperature of 90 degrees Celsius and a pressure of 280 psig (2031 kpa)) and nitrogen gas co-fed at 5 SCCM as an internal standard using mass flow controllers. The Fischer-Tropsch reaction product hydrocarbon liquids feed flow was sourced from a syngas conversion carried out in a reactor employing a cobalt-zeolite hybrid FT catalyst operating under catalytic conditions so as to form the FT reaction product. The FT reaction product feed was controlled by an Eldex® pump at 0.02 mL/min into the stainless steel tube reactor. The liquid vapor mixture gas exiting the tube reactor was chilled to 5°C with a spiral tube installed in an ethylene glycol bath. The cold separator condensed C4+ hydrocarbon product liquid and traces of water present in the feed. The remaining gas was then filtered through a coalescing filter to remove any entrained liquid droplets and directed to an Inficon™ Fusion Micro Gas Chromatograph for gaseous analysis. [0031] Conditions within the Reactor: Liquid flow was 1.92 grams of hydrocarbons per gram catalyst per hour. The reactor was held at 90°C, and the pressure was maintained at 280 psig (2031 kpa). The Liquid Hourly Space Velocity (LHSV) was 1.92 g/g catalyst/hour. The flow rate of the 95% H ₂ J 5% N ₂ gas mixture was 12000 SCC/gram catalyst/hour.

[0032] Simulated Distillation: An Agilent 7890B Gas Chromatograph with Flame Ionization Detector (GC-FID) was used to conduct a modified ASTM D2887 simulated distillation method. This method was used to provide a quantitative carbon number distribution for resulting liquid fuel samples in the hydrocarbon range C ₄ -C ₂₄ taken from the feed exiting the reactor at different times indicated for each sample in the accompanying Figures. Peak integrations were performed by referring to ASTM D5442. Calibration of the GC-FID was performed using the Supelco™ 47100, 47102, and 47108 n-paraffm mix standards for identification of straight-carbon chain peaks (C ₄ -C ₂₄ ). These pre-calibrated peaks were immediately identified during sample analysis while the rest of the peaks v ere classified according to retention time range. Decane linearity standards made through serial dilutions containing decane and hexadecane were analyzed before samples to ensure the Gas Chromatograph was linear.

[0033] Olefin Measurement Using Bromine Number method: The Bromine Number Determination for Olefin Content for the samples was undertaken using a TitraLab® AT1000 using a procedure developed from ASTM D1159-07 (2012). In this method the bromide-bromate titrant solution was calibrated using a 0.GN Sodium Thiosulfate solution. Precisely 1 mL of the bromide-bromate solution was added to the water-jacketed beaker on the stirrer platform that contained 50mL of acetic acid, 1 mL of concentrated HCL, 1 mL of potassium iodide (15Qg/L), and 50mL of deionized water. This analysis was performed twice, and the average titer value was input as the titer value into the Bromine Number analysis application on the instalment. After the successful calibration of the titrant, a blank determination was performed using 5mL of dichloromethane and 110 mL of cold (~3-5°C) titration solvent. The titration solvent was made up of 714 mL of acetic acid, 134 mL of dichloromethane, 134 mL of methanol, and 18 mL of sulfuric acid (1+5, i.e., 1 volume of concentrated sulfuric acid with 5 volumes of deionized water). Once a blank had been run that had a value of less than 0.1 mL, the sample analysis v-as performed. The samples were diluted in a 50 mL volumetric flask using dichloromethane. The chart below v-as used to determine how much sample was weighed.

The samples were analyzed three or four times, and the average value was reported. The instrument automatically calculated the bromine number for each sample analyzed, and from that the olefin content for each sample was determined.

[0034] The first sample taken (labeled 4/11/2017 in the accompanying figures and tables below) was the FT reaction product sample prior to entry into the oligomerization/hydrogenation reaction zone operating according to an aspect of the invention. All other labeled samples set forth in the figures and tables below were taken from the reaction product feeding out of the oligomerization/hydrogenation reaction zone. The following Table 1 provides the determined olefin content (wt% based on the total weight of the sample) of each of the samples taken.

[0035] The experiment was repeated to verify the results, and the following Table 2 sets forth the olefin content of each of the samples taken from the repeated run.

Table 2

[0036] The accompanying Fig. 1 shows the carbon content distribution (as determined by GC simulated distillation) of the sample of FT reaction product made from bringing together syngas and a cobalt-zeolite hybrid FT catalyst under FT reaction conditions, prior to the FT reaction product undergoing a catalytic reaction in accordance with this invention. Figs. 2-3 display the determined carbon content distribution of the hydrocarbons determined by GC simulated distillation of samples of hydrogenation reaction product made in the reactor operated in accordance with the invention and exiting the reactor at different times indicated on those figures. As can be seen from the accompanying Figs. 4A, 4B and 5, the reaction in the reaction zone results in a hydrocarbon distribution shift that lowers the aggregate amount of low carbon (<C ₇ ) hydrocarbon content and increased over time the content of hydrocarbons within the C ₈ - Ci ₆ range, while also reducing the overall olefins content (see in Tables 1 -2 above), as compared to the FT reaction product feed stock, from 39.99 wt% for the FT reaction product feed stock, to less than 1 wt.% olefins for the oligomerization/hydrogenation reaction product. Without wishing to be bound to theory, these results indicate that there is a dual catalytic oligomerization and hydrogenation conversion of the FT reaction product taking place in a single reaction zone operated under economically and operationally favorable reaction conditions. These observations were a surprisingly beneficial result, yielding an end product with jet fuel grade characteristics

[0037] While the foregoing is directed to describing various aspects of the invention, further aspects and embodiments of the invention may be devised without departing from the scope of the following claims.