AN IMPROVED PROCESS TO PRODUCE AROMATICS RICH AVIATION FUEL ALONG WITH OTHER C1-C24 HYDROCARBONS

Abstract

A single step catalytic process for the preparation of aromatic rich aviation fuel from renewable resource in the presence of a hydrogen stream, and one or more hydroprocessing catalysts, under operating conditions for hydroconversion reactions, as defined herein, with mixed hot and cold streams of the renewable feed and getting desired product after separation of water, lighter hydrocarbon gases and carbon oxides, the said product comprising of hydrocarbons C6-C24, rich in aromatic content in the aviation fuel range, including kerosene range.

Claims

1. A single step catalytic process for the preparation of aromatic rich aviation fuel from renewable resource feed in the presence of a hydrogen stream, and one or more hydroprocessing catalysts, under operating conditions for hydroconversion reactions, with a hot stream part of a renewable resource feed such as vegetable oils preheated to catalyst bed temperature, i.e. 250-500° C., and another part of the same renewable resource feed sent directly to the catalyst bed without pre-heating, and getting desired product after separation of water, lighter hydrocarbon gases and carbon oxides, the said product comprising of hydrocarbons C6-C24, rich in aromatic content in the aviation fuel range, including kerosene range.

2. The process according to claim 1, wherein cold streams in ratio varying between 1 to 100%, of the renewable resources feeds is processed with hot stream feed and both the streams undergo hydroconversion reactions.

3. The process according to claim 1, wherein renewable resource feed are vegetable oils such as jatropha oil karanj and algae.

4. The process according to claim 1, wherein the hydroconversion is performed in the presence of one or more metal sulfides of Group VI and/or Group VIII elements, at a pressure of from 40 to 110 bar, at an average temperature of the catalytic bed of from 250° C. to 500° C., at a space-velocity of from 0.511.sup.−1 to 311.sup.−1, and at a hydrogen load ratio of from 500 NL of hydrogen/L of mixture to 5000 NL hydrogen/L of mixture, to obtain a liquid hydrocarbon product with C6-C24 content of up to 100% and a boiling point in the range of gasoline, kerosene and diesel.

5. The process according to claim 1, wherein the kerosene range product can be maximized by direct injecting the cold liquid feed to the reactor (1-100% of total liquid feed) while controlling the exothermicity, utilizing the heat and maintaining the reactor bed temperature within the limit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1: Flow Methodology for Hot and cold feed use.

EXAMPLES

[0016] Below, the present invention is further described in detail by working Examples, to which the present invention is not limited. The products were analyzed by gas-chromatography, ASTM D6730 DHAX analysis. Simulated distillation of the products was carried out according to the ASTM-2887-D86 procedure. Total acidity number (TAN) was determined following ASTMD974 method.

Example 1

[0017] Jatropha oil was processed in a fixed bed reactor with sulfided Ni—Mo/SiO.sub.2—Al.sub.2O.sub.3. The reaction conditions for experiments were: 455° C., 100 bar, 0.95 h.sup.−1, and 3500 litre H.sub.2 gas/litre liquid feed. The ratio of hot and cold feed streams was 70:30 (hot liquid: 0.722 Lit/hr and Cold Liquid: 0.310 lit/hr) and the hydrogen partial pressure was maintained at 86 bar, recycle gas composition given below. The products were analyzed by gas-chromatography. Simulated distillation of the products carried out according to the ASTM-2887-D86 procedure showed that the products had 9.8% of product in diesel range (>C15) and 54.0% in kerosene range (C9-15) and complete conversion. ASTM D6730 DHAX analysis showed 8.5% aromatics in the kerosene range with isomer to normal hydrocarbon ratio (i/n) 2. Total acidity number (TAN) determined following ASTMD974 method was 0.15 mg KOH/g for the product.

Example 2

[0018] Jatropha oil was processed in a fixed bed reactor with sulfided Ni—Mo/SiO.sub.2—Al.sub.2O.sub.3. The reaction conditions for hydrotreating experiments were: 455° C., 100 bar, 1.01 h.sup.−1, and 3500 litre H.sub.2 gas/litre liquid feed. The ratio of hot and cold feed streams was 5:95 (hot liquid: 0.055 Lit/hr and Cold Liquid: 1.043 lit/hr) and the hydrogen partial pressure was maintained at 87 bar, recycle gas composition given below. The products were analyzed by gas-chromatography. Simulated distillation of the products carried out according to the ASTM-2887-D86 procedure showed 6.5% of product in diesel range (>C15) and 40.4% in kerosene range (C9-C15) with isomer to normal hydrocarbon ratio (i/n) 1.7 and complete conversion. ASTM D6730 DHAX analysis showed around 7.5% aromatics in the kerosene range. Total acidity number (TAN) determined following ASTMD974 method was 0.16 mg KOH/g for the product.

TABLE-US-00001 TABLE 1 Recycle gas composition Recycle H2 CO2 CO C1 C2 C3 C4 C5 % mole % mole % mole % mole % mole % mole % mole % mole % Exp 1 0.81 86.19 3.46 3.88 3.00 1.68 1.36 0.27 0.05 Exp2 0.81 87.39 2.88 3.94 2.19 1.50 1.65 0.35 0.10

TABLE-US-00002 TABLE 2 Product details and energy savings Temp. P WHSV <C9, C9-C15, >C15, i/n Energy Experiment (° C.) (bar) (h.sup.−1) H.sub.2/HC wt % wt % wt % aromatics (C9-C15) saved Comp. Ex. 455 100 1.01 3500 18.9 38.1 42.4  12% 1.77  0 kJ/kg 1 Ex. 1 455 100 0.95 3500 36.1 54.0 9.8 8.5% 2.00 700 kJ/kg Ex. 2 455 100 1.01 3500 53.1 40.4 6.5 7.5% 1.69 700 kJ/kg

Comparative Example 1

[0019] Jatropha oil was processed in a fixed bed reactor with sulfided Ni—Mo/SiO.sub.2—Al.sub.2O.sub.3. The reaction conditions for hydrotreating experiments were: 4550 C, 100 bar, 1.01 h-1, and 3500 ml H2 gas/ml liquid feed. The products were analyzed by gas-chromatography. The liquid feed was sent to the reactor through the pre-heater heated at 3700 C Simulated distillation of the products carried out according to the ASTM-2887-D86 procedure showed 38.1% middle range product (C9-C15) with isomer/normal hydrocarbon ratio 1.8 and complete conversion. ASTM D6730 DHAX analysis showed around 12% aromatics in the kerosene range.

Chemical Reactions:

[0020] The raise in temperature of the cold feed in the presence of catalytic materials leads to C—C coupling reactions along with other deoxygenation reactions such as hydro deoxygenation, decarboxylation and decarbonylation reactions. The unsaturates generated in the reaction media tend to undergo cyclization followed by aromatization. The lower hydrogen partial pressure 86 (Exp 1) & 87 (Exp 2) as compared to that in case of pure hydrogen make-up 100 bar also increases the tendency of these unstable molecule due to thermal cracking to undergo these changes. The exothermicity released due to deoxygenation heat of the reaction is utilized by the cold feed and is also used for further hydrocracking and isomerisation reactions with similar isomer to normal ratios and comparable C9-C15 yields.

Advantages

[0021] The present invention relates to a low energy catalytic process for the manufacture of the n-paraffins, iso-paraffins, cyclic and aromatics for aviation turbine fuel along with diesel and gasoline range hydrocarbons from renewable source such as oils originating from vegetable and animal fats with reduced exothermicities. The renewable feedstock (hot and cold streams) is converted into hydrocarbons by similar pathways such as decarboxylation/decarbonylation and hydrodeoxygenation along with cracking, isomerisation, cyclization and aromatization reactions. Better kerosene product and isomer selectivity is obtained by process conditions with controlled exothermicities (using same liquid feed, but adding cold feed along with pre-heated hot feed) and leading to desirable product pattern.

[0022] In the present invention, the use of cold feed not only controls the exothermicity of the reaction but the overall economy is improved. The energy utilized in heating the liquid feed is decreased by 700 kJ/Kg when cold feed is directly fed to the reactor along with preheated liquid feed. Moreover, the excess hydrogen which is generally required as quench to control the reactor bed temperature will not be required in this case. Additional quench gas would require large volume of all the equipments in the downstream of the reactor, and hence would require higher capital cost compared to that without gas quench stream.

[0023] In the present invention, the use of cold feed, decreased the heavier component in the product stream drastically, which is highly beneficial for the production of lighter and middle distillate component. The ratio of isomer/normal hydrocarbon is also observed to be increased.