RU2602278C1 - Catalyst and process of hydrodeoxygenation of vegetal raw materials and its application - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to catalysts for hydrodeoxygenation and process for hydrodeoxygenation of vegetable oils containing triglycerides of fatty acids in order to obtain hydrocarbons of diesel fraction. Catalyst for hydrodeoxygenation of vegetal raw materials includes active component comprising molybdenum and phosphorus, dispersed on aluminum oxide carrier, as carrier it contains composition of aluminium oxide and zeolite β, which includes, wt%: 0.42-0.53 of magnesium compounds in terms of MgO, 7.56-9.82 of silicon compounds in terms of SiO₂, aluminium oxide is the rest, and as an active component, catalyst contains, wt%: molybdenum 12.5-13.5, phosphorus 1.8-2.2. Process is carried out at temperature of 220-300 °C, hydrogen pressure 4.0 MPa, volume rate of consumption of raw materials is 2.0 h^-1, volume ratio hydrogen/material is 600 Nm³/m³, and used catalyst is catalyst with above composition.

EFFECT: complete conversion of oxygen-containing compounds on route of straight hydrodeoxygenation, during which carbon oxides are not formed.

2 cl, 1 tbl, 4 ex

Description

The invention relates to hydrodeoxygenation catalysts and a process for hydrodeoxygenation of vegetable oils containing fatty acid triglycerides in order to produce diesel hydrocarbons.

In the face of declining global oil reserves, there is a tendency to increase demand for environmentally friendly motor fuels. In this regard, the development and implementation of new catalytic technologies for the processing of renewable raw materials into motor fuels is relevant today. Non-edible vegetable oils, pyrolysis products of various biomasses, etc. are used as renewable raw materials. [J.K. Satyarthi, T. Chiranjeevi, D.T. Gokak, P.S. Viswanathan, An overview of catalytic conversion of vegetable oils / fats into middle distillates, Catalysis Science & Technology, 3 (2013) 70-80; M. Al-Sabawi, J.W. Chen, Hydroprocessing of Biomass-Derived Oils and Their Blends with Petroleum Feedstocks: A Review, Energy & Fuels, 26 (2012) 5373-5399; E. Furimsky, Hydroprocessing challenges in biofuels production, Catalysis Today, 217 (2013) 13-56].

The production of components that are fully compatible with diesel fuel from renewable raw materials is based on hydrofining of fatty acid triglycerides into a mixture of alkanes, which is called in the literature second-generation biodiesel, bio-gasoil or green diesel. This product does not contain oxygen, is characterized by a high cetane index and stability, is mixed with traditional diesel fuel in any proportions, which allows you to use the existing infrastructure for its transportation and storage and does not require the adaptation of automobile engines.

In industrial processes for the processing of fatty acid triglycerides, traditional sulfide catalysts Co (Ni) Mo (W) are used for hydrotreating (US 8884086, C10G 11/00, 11/11/2014: US 8026401, С07С 27/02, 09/27/2011). It is known that hydrodeoxygenation reactions proceed along two routes: hydrogenation with the formation of water as a by-product and decarbonylation / decarboxylation with the formation of carbon oxides CO / CO ₂ . The conversion of oxygen-containing raw materials on bimetallic sulfide Co (Ni) Mo (W) catalysts occurs mainly through the decarboxylation / decarbonylation route. The carbon oxides formed as a result of the reaction can be hydrogenated, which leads to additional heating of the reactor and a higher consumption of hydrogen. In addition, the purification of recycle gas, hydrogen, from the formed methane and carbon monoxide is technically difficult and expensive.

The composition of vegetable oils includes carboxylic acid residues with the number of carbon atoms C ₁₈ -C ₂₂ , and to improve the low-temperature properties of the resulting diesel fuel, an additional isomerization step is required, which is carried out with the participation of noble metal catalysts (US 2008/0163543 A1, C10L 1 / 18, 07/10/2008; US 8546626, B01J 21/02, 01/10/2013). These catalysts are deactivated in the presence of carbon oxides and hydrogen sulfide formed upon decomposition of the sulfurizing agent. At the same time, hydrogen sulfide and CO ₂ , unlike carbon monoxide, are easily removed.

It is known that the conversion of oxygen-containing compounds on a supported or bulk MoS ₂ catalyst proceeds along the direct hydrodeoxygenation route while maintaining the number of carbon atoms, i.e. without the formation of carbon oxides [MR de Brimont, C. Dupont, A. Daudin, C. Geantet, P. Raybaud, Deoxygenation mechanisms on Nipromoted MoS ₂ bulk catalysts: A combined experimental and theoretical study, Journal of Catalysis, 286 (2012) 153 -164; D. Kubicka, L. Kaluza, Deoxygenation of vegetable oils over sulfided Ni, Mo and NiMo catalysts, Applied Catalysis A-General, 372 (2010) 199-208]. In this regard, this catalyst can be used in a two-stage process of processing plant materials, which includes the isomerization stage using catalysts based on noble metals (US 8546626, B01J 21/02, 01/10/2013). In the patent US 8546626, B01J 21/02, 01/10/2013 for the hydrodeoxygenation of rapeseed oil, a sulfide MoP / Al ₂ O ₃ catalyst is used, while the complete conversion of oxygen-containing compounds is achieved at a temperature of 300 ° C, a hydrogen pressure of 5.0 MPa, a volumetric flow rate raw materials - 2.0 h ^-1 , the volume ratio of hydrogen / raw materials - 700 Nm ³ / m ³ .

Closest to the proposed technical solution is a patent (US 8026401, C07C 27/02, 09/27/2011), which describes a two-stage process of hydrodeoxygenation of bio-raw materials using two industrial catalysts. The installation for this process consists of two series-connected reactors, in the first of which Mo / Al ₂ O ₃ is loaded, and in the second NiMo / Al ₂ O ₃ catalyst. In this case, a partial conversion of oxygen-containing compounds is carried out on the Mo / Al ₂ O ₃ catalyst, and a complete conversion is achieved on the NiMo / Al ₂ O ₃ catalyst. In addition, the hydrodeoxygenation process is carried out under rather severe conditions (11.0 MPa, Τ - 310-340 ° C).

A common disadvantage for the prototype is that the used Μo / Αl ₂ Ο ₃ catalyst exhibits insufficient activity in the conversion of oxygen-containing compounds.

The invention solves the problem of developing an effective catalyst for hydrodeoxygenation, as well as a method for using this catalyst to obtain components of a diesel fraction from plant materials containing fatty acid triglycerides.

The problem is solved by using a catalyst in the process of hydrodeoxygenation of plant materials, including the active component, which includes molybdenum and phosphorus dispersed on a carrier, as a carrier, it contains a composition of aluminum oxide and zeolite β, which includes, wt. %: 0.42-0.53 magnesium compounds in terms of MgO, 7.56-9.82 silicon compounds in terms of SiO ₂ , aluminum oxide - the rest; and as an active component, the catalyst contains, by weight. %: molybdenum 12.5-13.5, phosphorus 1.8-2.2, the carrier - the rest.

The problem is also solved by the method of hydrodeoxygenation of plant raw materials, which consists in passing the raw material through the catalyst bed at a temperature of 220-300 ° C, a hydrogen pressure of 4.0 MPa, a volumetric flow rate of feedstock of 2.0 h ^-1 , a volumetric ratio of hydrogen / raw material of 600 Nm ³ / m ³ .

The optimization of the composition of the carrier is achieved by the fact that it additionally contains zeolite β in the amount, wt. %: 10-15, while to reduce the number and strength of acid sites that cause cracking of hydrocarbon molecules and deactivation of the catalyst due to carbon deposits, zeolite powder β is pre-treated with a 30% solution of Mg acetate and contains 3.1-3.3 wt. % Mg. The carrier is prepared by the method described in patent RU 2468864, B01J 23/85, 12/10/2012.

Distinctive features of the proposed catalyst and method of hydrodeoxygenation of plant materials containing triglycerides of fatty acids are:

1. The composition of the catalyst, including compounds of Mo and Ρ as the active component in an amount, wt. %: molybdenum 12.5-13.5, phosphorus 1.8-2.2; which is dispersed on the surface of the carrier, as a carrier, it contains a composition of alumina and zeolite β, the following composition, wt. %: 0.42-0.53 magnesium compounds in terms of MgO, 7.56-9.82 silicon compounds in terms of SiO ₂ , aluminum oxide - the rest, characterized by a specific surface area of 240 m ² / g, an average pore diameter of 9.0-9.5 nm.

2. The method of hydrodeoxygenation of plant materials containing fatty acid triglycerides, which is carried out in a hydrotreatment reactor loaded with a hydrodeoxygenation catalyst described above.

The above composition and the proposed method of hydrodeoxygenation can improve the efficiency of the hydrodeoxygenation process of plant materials containing fatty acid triglycerides.

EFFECT: complete conversion of oxygen-containing compounds along the direct hydrodeoxygenation route, during which carbon oxides are not formed.

The determination of the activity of catalysts in the process of hydrodeoxygenation of plant materials containing fatty acid triglycerides is carried out in a flow reactor with an internal diameter of 16 mm and a length of 570 mm. Raw materials and hydrogen enter the reactor from top to bottom: the initial mixture is fed using a Gilson-305 liquid chromatographic pump, and hydrogen is dosed with a Bronkhorst automatic dispenser. In each experiment, the hydrodeoxygenation catalyst is loaded into the central part of the reactor, the catalyst volume is 10 ml. Granules of the catalyst with a length of 3-6 mm are loaded into the reactor, uniformly diluted with silicon carbide particles with a size of 0.1-0.2 mm in a volume ratio of 1: 2. Sulfidation of the catalysts is carried out with a mixture of dimethyl disulfide (DMDS) in tetradecane containing 0.6 wt. % sulfur. The volumetric feed rate of the sulfidation mixture is 2 h ⁻¹ , the hydrogen / feed ratio is 300 Nm ³ / m ³ . Sulfidation is carried out in two stages: at a temperature of 240 ° C for 8 hours, at a temperature of 340 ° C for 6 hours, the rate of temperature increase between stages does not exceed 25 ° C per hour. After the sulfidation procedure is completed, the hydrogen pressure is increased to a predetermined value, and the reaction mixture is dispensed into the reactor. Testing of the catalysts is carried out at a volumetric feed rate of 2.0 h ^-1 , a hydrogen / feed ratio of 600 Nm ³ / m ³ , a pressure of 4.0 MPa at a temperature of 220-300 ° C.

The total proportion of oleic, linoleic, linolenic and stearic acids in rapeseed oil is about 93%. As a result, the ratio of C ₁₈ / C ₁₇ in the reaction products can serve as an indicator reflecting the selectivity of conversion along the hydrodeoxygenation or decarbonylation / decarboxylation routes.

The invention is illustrated by the following examples.

Examples 1-3 illustrate the composition of the catalyst and the method of its preparation.

Example 1

The catalyst carrier was prepared according to the procedure described in patent RU No. 2468864. The content of components in the sample carrier is, wt. %: 0.42 magnesium compounds in terms of MgO, 7.56 silicon compounds in terms of SiO ₂ , aluminum oxide - the rest; characterized by a specific surface area of 246 m ² / g, a pore volume of 0.55 cm ³ / g, an average pore diameter of 9.5 nm.

The catalyst is prepared by impregnating the carrier granules with an aqueous solution obtained by dissolving molybdenum trioxide, phosphoric and citric acids. Heat treatment of the obtained catalyst is carried out in a stream of nitrogen at room temperature to a free-flowing state, then in an air stream at a temperature of 110 ° C for 12 hours. To determine the content of active components, the catalyst is calcined in a muffle at a temperature of 550 ° C for 4 hours, the content of active components in the catalyst is, wt. %: Mo - 13.5, Ρ - 1.8 (designation of the catalyst MoP / AC-10).

For testing, use 10 ml of the proposed catalyst in the form of granules with a diameter of 1.3 mm and a length of 3-6 mm. As the feedstock use 10 wt. % rapeseed oil in tetradecane. To maintain the active sulfide phase during the hydrodeoxygenation process, dimethyl disulfide in an amount of 0.6 wt. % sulfur.

Before carrying out catalytic tests, the catalyst is sulfidized with a mixture of DMDS in tetradecane in an amount of 0.6 wt. % sulfur according to the above procedure.

The catalytic properties of the obtained sample in the process of hydrodeoxygenation of rapeseed oil are determined by varying the temperature in the range 220-300 ° C, hydrogen pressure 4.0 MPa, the ratio of H ₂ / feedstock - 600, the volumetric feed rate of the feedstock - 2.0 h ^-1 .

Example 2

The catalyst according to example 1, in which according to the invention, extrudates with a zeolite content of β - 15 wt. % After calcination, the extrudates contain, by weight. %: 0.53 magnesium compounds in terms of MgO, 9.82 silicon compounds in terms of SiO ₂ , aluminum oxide - the rest; characterized by a specific surface area of 240 m ² / g, a pore volume of 0.51 cm ³ / g, an average pore diameter of 9.0 nm. The content of active components in the catalyst is, wt. %: Mo - 12.5, Ρ - 2.2 (designation of the catalyst MoP / AC-15).

Examples 3-4 are given for comparison.

Example 3

The catalyst according to example 1, in which according to the invention, γ-Al ₂ O ₃ is used as a carrier in the form of granules with a cross section in the form of a trefoil 1.2 mm in size, characterized by a specific surface area of 235 m ² / g, a pore volume of 0.79 cm ³ / g, an average pore diameter of 95 Å. The content of active components is, wt. %: Mo - 13.3, Ρ - 2.1 (catalyst designation ΜoΡ / Αl ₂ Ο ₃ ).

Testing of the catalyst is carried out as in example 1, the indicators of the hydrodeoxygenation process are presented in the table.

Example 4

The catalyst according to example 2, in which according to the invention, cobalt hydroxide is added to the impregnation solution. The content of active components is, wt. %: Co - 3.5, Mo - 12.5, Ρ - 1.8 (catalyst designation CoMoR / AC-15).

Testing of the catalyst is carried out as in example 1, the indicators of the hydrodeoxygenation process are presented in the table.

Example 5 illustrates rapeseed oil hydrodeoxygenation processes.

Example 5

10 ml of the proposed catalyst in the form of granules with a cross section in the form of a trefoil with a diameter of 1.3 mm and a length of 3-6 mm, prepared according to example 1, is loaded into a flow reactor. The catalysts are sulfidized with a mixture of DMDS in tetradecane with a sulfur concentration of 0.6 wt. % in two stages: at a temperature of 240 ° C for 8 hours and at 340 ° C - 6 hours. Testing of the catalysts is carried out with a temperature variation in the range of 220-300 ° C, a hydrogen pressure of 4.0 MPa, a ratio of H ₂ / feed - 600, the volumetric feed rate of the raw material is 2.0 h ^-1 . As the feedstock use 10 wt. % rapeseed oil in tetradecane. The duration of each stage is 8 hours.

The indicators of the hydrodeoxygenation process are presented in the table.

As can be seen from the above examples, the proposed zeolite-containing catalysts provide a complete conversion of oxygen-containing compounds already at 260 ° C, while the main route for their conversion is direct hydrodeoxygenation, as a result of which carbon oxides are not formed. When using a CoMoR / AC-15 catalyst under the same conditions, despite the high activity in hydrodeoxygenation reactions, the conversion of oxygen-containing compounds occurs not only along the direct hydrodeoxygenation route, but also through the decarboxylation / decarbonylation route, resulting in the formation of undesired reaction products - carbon oxides .

Thus, the proposed catalysts allow efficient hydrodeoxygenation at lower energy costs with the complete conversion of oxygen-containing compounds along the direct hydrodeoxygenation route, during which carbon oxides are not formed.

Claims (2)

1. The catalyst for the process of hydrodeoxygenation of plant materials, including the active component, which includes molybdenum and phosphorus dispersed on an alumina carrier, characterized in that as a carrier it contains a composition of aluminum oxide and zeolite β, which includes, wt. %: 0.42-0.53 compounds of magnesium in terms of MgO, 7.56-9.82 compounds of silicon in terms of SiO ₂ , aluminum oxide - the rest, and as an active component, the catalyst contains, wt. %: molybdenum 12.5-13.5, phosphorus - 1.8-2.2. 2. The method of hydrodeoxygenation of plant materials containing fatty acid triglycerides, which consists in passing the feed through a catalyst bed, characterized in that the process is carried out at a temperature of 220-300 ° C, a hydrogen pressure of 4.0 MPa, a volumetric flow rate of the feed - 2.0 h ^-1 , the volume ratio of hydrogen / raw materials is 600 Nm ³ / m ³ , and the catalyst according to claim 1 is used as a catalyst.