TWI415930B - A process for reducing the total acid number (tan) of a liquid hydrocarbonaceous feedstock - Google Patents

Abstract

A process for reducing the total acid number (TAN) of a liquid hydrocarbonaceous feedstock, wherein the feedstock is contacted, in the presence of a hydrogen-containing gas and at a temperature in the range of from 200 to 400° C. and at elevated pressure, with a catalyst comprising an oxide of a metal of Column 3 or 4 of the Periodic Table of Elements or of a lanthanide, which catalyst is essentially free of Column 5 to 10 metals or compounds thereof, to obtain a liquid hydrocarbonaceous product with a reduced total acid number.

Description

Method for reducing total acid value (TAN) of liquid hydrocarbon-containing feedstock

The present invention provides a method of reducing the total acid number (TAN) of a liquid hydrocarbonaceous feedstock, particularly crude oil.

Crude oils with high acid content and other liquid hydrocarbon-containing liquid streams are difficult to refine. Especially for distillation units in crude oil refineries, high acid content can cause corrosion problems. It is well known that acids can be removed by hydrotreating, i.e., by removing the other heteroatoms such as sulfur and nitrogen from the liquid hydrocarbonaceous feedstock. However, the hydrotreating is a process carried out downstream of the refinery's distillation unit.

In order to avoid corrosion problems due to the acid content of the crude oil, it is common to blend different crude oil streams to obtain a crude feed having an acceptable acid content.

The acid content of crude oil or other hydrocarbon-containing liquids is usually expressed as the total acid number (TAN) of such liquids. The TAN system represents the number of milligrams of KOH required to neutralize the acid per gram of liquid, according to the procedure disclosed in ASTM D664.

Accordingly, there is a need in the art for a method for reducing TAN in a liquid hydrocarbon-containing liquid stream (e.g., crude oil) used as a feedstock in a refinery, and for converting sulfur- and nitrogen-containing compounds and unsaturated hydrocarbons to a minimum. By this means, an acceptable refinery feedstock can be obtained with minimal hydrogen consumption.

Catalysts which are substantially free of hydrogenation components (i.e., compounds of any of the metals of Groups 5 to 10 of the Periodic Table of Elements) have been found to be useful for the selection of acids in liquid hydrocarbon-containing streams, particularly crude oils. In the hydrogenation reaction, the hydrogenation reaction component is typically used in a hydroconversion reaction such as a hydrodesulfurization reaction, a hydrodenitrogenation reaction, and a hydrocracking reaction.

Accordingly, the present invention provides a method of reducing the total acid number (TAN) of a liquid hydrocarbon-containing feedstock, wherein the feedstock is in the presence of a hydrogen-containing gas, and at a temperature ranging from 200 to 400 ° C and under pressurized conditions Contact with a catalyst comprising a metal oxide of Group 3 or 4 of the Periodic Table of the Elements or a lanthanide element (the catalyst is substantially free of a metal of Groups 5 to 10 or a compound thereof) to obtain a reduction in total acid value Liquid hydrocarbon-containing products.

An advantage of the process according to the invention is that the total acid number of the feedstock is reduced by the hydrogenation reaction, while other hydrogenation reactions such as hydrodesulfurization, hydrodenitrogenation and saturation of unsaturated hydrocarbons can be minimized.

According to the process of the present invention, the liquid hydrocarbon-containing feedstock is present in the presence of a hydrogen-containing gas, and at a temperature ranging from 200 to 400 ° C and under pressure, and comprising a Group 3 or 4 or a lanthanide of the Periodic Table of the Elements. The catalyst of the metal oxide is contacted, wherein the catalyst is substantially free of a metal of Groups 5 to 10 or a compound thereof.

The feedstock can be any liquid hydrocarbon-containing liquid stream containing a carboxylic acid (i.e., an organic acid). This method is particularly suitable for use in feedstocks containing naphthenic acids. Preferably, the feedstock is a crude oil, a distillate stream (e.g., light oil or gas oil), a residue component of atmospheric crude oil distillation, or a hydrocarbon-containing distillation product (e.g., a heating oil) that does not conform to the TAN product specification. The process according to the invention is particularly suitable for reducing the total acid value of crude oil.

The hydrogen-containing gas is preferably hydrogen or syngas. The use of syngas as a hydrogen-containing system is particularly advantageous where hydrogen is not available at remote locations such as offshore oil rigs.

The temperature and pressure at which the feedstock is contacted with the catalyst can cause the carboxylic acid to undergo a hydrogenation reaction, i.e., at least 200 °C. This temperature is lower than the temperature at which the carboxylic acid is thermally decomposed, that is, lower than 400 °C. The temperature is preferably in the range of 250 to 390 ° C, more preferably in the range of 300 to 380 ° C.

The method is carried out under pressure, that is, above normal pressure. The pressure is preferably in the range of 2 to 200 bar g, more preferably 10 to 150 bar g, and still more preferably in the range of 25 to 120 bar g.

The catalyst is a metal oxide of Group 3 or 4 or a lanthanide element of the Periodic Table of the Elements (the latest IUPAC name). The oxide may also be a mixed oxide of two or more of these metals. The catalyst may also comprise a mixture of two or more of these oxides. The catalyst is essentially a metal that does not contain Groups 5 to 10 of the Periodic Table of the Elements (the latest IUPAC name) or a compound thereof. The term "catalyst substantially free of certain compounds" as used herein means that such compounds are not contained, except in very small amounts, typically in the ppm range or lower, which may be unintentional contamination, or in order to obtain The mineral refining step of the Group 3 or 4 metal or lanthanide oxide is left over.

The catalyst is preferably an oxide comprising a Group 4 metal or a lanthanide. Preferred Group 4 metal oxides are titanium oxide and zirconium oxide, and preferred lanthanide oxides are cerium oxide. More preferably, the catalyst is composed of titanium oxide and/or zirconium oxide, and more preferably composed of zirconium oxide.

The catalyst system can be prepared by any of the manufacturing methods known in the art. The catalyst is preferably made to have a specific surface area of at least 10 m ² /g, more preferably at least 30 m ² /g.

The starting materials for use in the process according to the invention preferably have a total acid number of at least 0.2 mg KOH per gram of starting material, preferably at least 0.5 mg KOH per gram of starting material, and more preferably at least 1.0 mg KOH per gram of starting material. The term "total acid value" as used herein means KOH (in milligrams) per gram of raw material as measured by ASTM D664.

The liquid hydrocarbon-containing product is preferably a TAN having a raw material of at most 0.2 mg KOH/g, more preferably at most 0.1 mg KOH/g of the raw material, and still more preferably at most 0.05 mg KOH/g of the raw material.

Preferably, the TAN is reduced such that the total acid number of the liquid hydrocarbon-containing product having a reduced total acid number is at most 50%, more preferably at most 30%, of the TAN of the feedstock.

Example Hydrogenation step

In a microfluidic reactor, crude oil and solid inert material (0.1 mm niobium carbide particles), or a catalyst as described below (catalyst particles diluted with niobium carbide particles: 1/1 v/v) Contacting in the presence of a hydrogen containing gas or nitrogen for at least 100 hours. Two different crude oils are used. In Test Examples 1 to 8 and 13 to 16, West African crude oil ("crude oil 1") was used; in Test Examples 9 to 12, crude oil obtained from the Middle East ("crude oil 2") was used. The specifications for the two crude oils are shown in Table 1. The precise conditions of each test are provided in Table 2.

The total acid number (TAN) of the liquid effluent from each test was measured according to ASTM D664. The concentration of hydrogen sulfide in the vapor phase effluent is determined by gas chromatography. The TAN of the liquid effluent in the vapor phase effluent and the concentration of hydrogen sulfide in the vapor phase effluent are also shown in Table 2.

Test Examples 3, 4, 6, 7, 9, 10, 12 and 14 to 16 are tests according to the present invention. Test Examples 1, 2, 5, 8, 11 and 13 are comparative test examples.

catalyst

The following catalysts were used in the hydrogenation reaction test.

The titanium oxide catalyst 1 titanium oxide catalyst (hereinafter referred to as "titanium oxide 1") was obtained as follows. A titanium oxide powder (P25, manufactured by Degussa Co., Ltd.; combustion loss: 4.4% by weight at 540 ° C) in an amount of 3,192 g was mixed with 100 g of oxalic acid dihydrate in a mixing-grinding kneader (Simpson). After mixing-milling for 4 minutes, 981 grams of deionized water and 100 grams of polyethylene glycol were added and mixing continued - grinding for 12 minutes. Then, 100 grams of methylcellulose was added and mixing was continued - grinding for 20 minutes. The mixture thus formed was molded by extrusion using a 1.7 mm diameter clover type die plate. The clover type was dried at 120 ° C for 2 hours and calcined at 500 ° C for 2 hours.

The surface area of the obtained titanium oxide clover type measured by a nitrogen gas adsorption method (BET method) was 52 m ² /g, and the pore volume measured by a mercury injection method was 0.31 ml/g.

As the titanium oxide catalyst 2 , titanium oxide fine particles commercially available as X096 (manufactured by CRI Catalyst) are used as a titanium oxide catalyst (hereinafter referred to as "titanium oxide 2"). The surface area of these titanium oxide fine particles measured by a nitrogen gas adsorption method (BET method) was 120 m ² /g, and the pore volume measured by the mercury injection method was 0.32 ml/g.

Zirconia Catalyst The zirconia catalyst was prepared as follows. A quantity of 264 g of zirconia powder (RC100, manufactured by Daiichi Co., Ltd.; combustion loss: 5.3 wt% at 540 ° C) and 90 g of a solution containing 5 wt% of polyvinyl alcohol in deionized water are The kneader (Werner & Pfeider Sigma Kneader type LUK 0.75) was mixed. After kneading for 7 minutes, 2.5 g of cationic polypropylene decylamine (Superfloc, manufactured by Cytec Co., Ltd.) was added, and after further kneading for 20 minutes, 8 g of deionized water was added. The mixture was kneaded again for 22 minutes. The mixture thus formed was formed into a 1.7 mm diameter clover type using an extrusion method. The extrudate was dried at 120 ° C for 2 hours and calcined at 500 ° C for 2 hours.

The surface area of the obtained zirconia clover type measured by a nitrogen gas adsorption method (BET method) was 54 m ² /g, and the pore volume measured by a mercury injection method was 0.35 ml/g.

NiMo on alumina uses a conventional hydrodesulfurization catalyst comprising Ni (nickel) and Mo (molybdenum) supported on alumina, which is commercially available as CRITERION RM-5030 (Criterion Catalyst).

a WHV: Weight per hour, ie kilograms of oil per kilogram of catalyst per hour. In Test Examples 1 and 2, the catalyst was not contained and the WHV for comparison could not be defined (the hourly weight velocity of the oil in Test Examples 1 and 2 was 1.1 kg/kg SiC/hour). b gas ratio (expressed as normal liter gas per kg of oil). c Total acid number (TAN) (expressed as milligrams KOH per gram of oil). d not determined; the liquid effluent does not have the smell of hydrogen sulfide. e is not determined; the liquid effluent has the smell of hydrogen sulfide. f Syngas composition: 33.2% by volume of hydrogen; 20.7% by volume of CO; others are nitrogen.

Claims (10)

A method for reducing the total acid number (TAN) of a liquid hydrocarbon-containing feedstock, wherein the feedstock is in the presence of a hydrogen-containing gas, and at a temperature ranging from 200 to 400 ° C under pressurized conditions and comprising an elemental periodic table The catalyst of the metal oxide of Group 3 or 4 or a lanthanide element is contacted (the catalyst is substantially free of a metal of Groups 5 to 10 or a compound thereof) to produce a liquid hydrocarbon-containing product having a reduced total acid number. . The method of claim 1, wherein the oxide is a Group 4 metal or a lanthanide oxide, and is preferably titanium oxide or zirconium oxide, more preferably zirconia. The method of claim 2, wherein the catalyst consists essentially of titanium oxide and/or zirconia. A method according to any one of the preceding claims, wherein the pressure is in the range from 2 to 200 bar g, preferably from 10 to 150 bar g, and more preferably from 25 to 120 bar g. The method of any one of the preceding claims, wherein the temperature is in the range of from 250 to 390 ° C, preferably from 300 to 380 ° C. The method of any of the preceding claims, wherein the hydrogen-containing gas is syngas or hydrogen. The method of any of the preceding claims, wherein the raw material has a TAN of at least 0.2 mg KOH per gram of material, preferably at least 0.5 mg KOH per gram of material, and more preferably at least 1.0 mg KOH per gram of material. . The method of any of the preceding claims, wherein the liquid hydrocarbon-containing product has a TAN of at most 0.2 mg KOH per gram of material, preferably at most 0.1 mg KOH per gram of material, and more preferably at most It is 0.05 mg KOH / gram of raw material. The method of any of the preceding claims, wherein the TAN of the liquid hydrocarbon-containing product having a reduced total acid number is at most 50%, and preferably at most 30%, of the TAN of the crude product. The method of any of the preceding claims, wherein the liquid hydrocarbon-containing feedstock is crude oil.