CN1258503C - A kind of method for preparing isooctane - Google Patents

Abstract

The present invention relates to a method for preparing isooctane, which belongs to the field of fine petrochemical industry. In the method, mixed octene (mixed C8 alkene) is used as a raw material; firstly, a cobalt catalyst or a rhodium catalyst is treated with hydroformylation reaction to obtain isononanal under mild reaction conditions, and unreacted isooctene (trimethylpentene) is further treated with hydrogenation to obtain isooctane (trimethylpentane), wherein the reaction temperature is from 100 to 160 DEG C, the reaction pressure is from 7 to 8MPa, and a palladium/activated carbon catalyst is used as a hydrogenation catalyst. In the present invention, the mixed octene hydroformylation technology is combined with unreacted isooctene raw material hydrogenation technology, and the isononanal and the isooctane are simultaneously prepared. Thus, raw materials can be fully used, and two products with high added value can be obtained. Thereby, the present invention has the advantages of great economic benefit and simple technology, and is suitable for industrialized production.

Description

A kind of method for preparing isooctane

technical field

The invention relates to a method for preparing isooctane, which belongs to the field of fine petrochemical industry. The method is to use mixed octene (mixed C ₈ alkene) as raw material, after hydroformylation reaction to obtain isononanal (mixed C ₉ aldehyde), unreacted isooctene (trimethylpentene) is further added Hydrogen gives isooctane (trimethylpentane).

Background technique

Isooctane is an important organic chemical used as a gasoline additive to increase the octane number of gasoline. Industrially, a mixture of C ₈ alkanes rich in isooctane can be obtained by hydrogenating mixed octene (such as Chinese Patent Publication No. 1381549, US Patent US 08-975867). Mixed octene can be obtained by oligomerization of butene. Due to the different catalysts and processes used, the types and quantities of various isomers contained in mixed octene after butene oligomerization are also different, mainly containing trimethylpentene, dimethylhexene, formaldehyde Branched internal alkenes such as heptene.

In industrial production, isononanal can be prepared by mixing octene and synthesis gas through a hydroformylation process. Isononanal is an important organic chemical and a raw material for a plasticizer (diisononyl phthalate) with excellent performance. The industrial catalyst that is used for hydroformylation process mainly contains cobalt series catalyst and rhodium series catalyst (as US Pat.3239566), US Pat.3527809, US Pat.4247486, US Pat.5105018). Since mixed octene is a high-carbon branched internal alkene, the octene molecule has 1 to 3 branched methyl groups, and the double bond is not at the end, so the reactivity of hydroformylation is relatively low. For high-carbon branched internal olefins, US Patent No. 4528403 invented a rhodium/triphenylphosphine oxide catalyst system applied to the hydroformylation process of mixed octene. The modified cobalt catalyst is also used in the hydroformylation process of mixed octene to prepare isononanal, see Chinese patent application number: 200410062259.5.

Among the different isomers of mixed octene, the reactivity of hydroformylation is trimethylpentene<dimethylhexene<methylheptene, and internal alkenes<terminal alkenes. Mixed octene can be hydroformylated into isononanal in the presence of a modified rhodium catalyst or a modified cobalt catalyst, but the trimethylpentene contained in the raw material is difficult to convert. If harsh reaction conditions (such as high reaction temperature and increased synthesis gas pressure) are used, although trimethylpentene can be converted, the by-products of the reaction increase, and the process conditions are harsh and the cost is increased, which is economically unfavorable. If the unreacted isooctene (trimethylpentene) after the hydroformylation of mixed octene is hydrogenated into isooctane (trimethylpentane), the utilization value of mixed octene raw material is greatly improved, Economically very favorable. On the other hand, although the direct hydrogenation of mixed octene obtained from butene oligomerization can also obtain a mixture of various isomeric octanes, only trimethylpentane is the best additive to increase the octane number of gasoline, while mixed The dimethylhexene and methylheptene contained in octene are converted into corresponding alkanes by hydrogenation, and their utilization value is far lower than that of trimethylpentane, and further separation of various octane isomers is economical. It's not good either. Therefore, combining the mixed octene hydroformylation process with the unreacted isooctene raw material hydrogenation process, producing iso-octane while producing isononanal, can make full use of raw materials and obtain two kinds of high added value The product is economically advantageous and simple in process.

Contents of the invention

The purpose of the present invention is to provide a kind of method that has industrial application value, produces isononanal and isooctane from mixed octene.

The present invention takes mixed octene as raw material, uses cobalt catalyst or rhodium catalyst to carry out hydroformylation reaction under mild reaction conditions to obtain isononanal, isooctene (trimethylpentene) in unreacted mixed octene Further hydrogenation yields isooctane (trimethylpentane).

A kind of method for preparing isooctane proposed by the present invention is characterized in that: the method uses mixed octene as raw material, uses cobalt catalyst or rhodium catalyst to carry out hydroformylation reaction under mild reaction conditions to obtain isononanal, The isooctene in the unreacted mixed octene is further hydrogenated (palladium/activated carbon catalyst) to obtain isooctane, and its processing steps are as follows:

(1) Mixed octene hydroformylation reaction process: In a high-pressure reactor, add a certain amount of cobalt acetate or dimerized rhodium acetate, phosphine oxide ligand, mixed octene and solvent, and place the reactor in a heating furnace after it is sealed In the process, after replacing the air in the reactor with synthesis gas (CO/H ₂ =1/1), the reactor is heated to the reaction temperature, and at a given reaction temperature, the reactor is filled with synthesis gas (CO/H ₂ =1/1) to reaction pressure, under reaction temperature and reaction pressure, stirring reaction, in reaction process, supply synthesis gas continuously and keep reaction pressure stable;

(2) Separation process of hydroformylation product: After the hydroformylation reaction is over, take the reaction kettle out of the heating furnace, cool it to room temperature, reduce the pressure in the reaction kettle to normal pressure, open the lid of the kettle, take out the mixed Liquid, mixed solution is carried out underpressure distillation, separation catalyst and product isononanal and unreacted raw material isooctene (trimethylpentene);

(3) Hydrogenation and separation process of unreacted raw material isooctene (trimethylpentene): add the isooctene obtained by distillation and separation into the reactor, add palladium/activated carbon catalyst, and place the reactor after sealing In the heating furnace, after replacing the air in the reactor with hydrogen (H ₂ ), heat the reactor to the reaction temperature, and fill the reactor with hydrogen to the reaction pressure at the given reaction temperature; Under stirring, react for 2.5 hours; during the reaction, supply hydrogen continuously and keep the reaction pressure stable; At normal pressure, open the lid of the kettle, take out the mixed solution of the catalyst and the product and separate it to obtain isooctane.

In the above method for preparing isooctane, the reaction temperature in the step (3) is 100-160°C.

In the above method for preparing isooctane, the reaction pressure in the step (3) is 7-8 Mpa.

The invention combines the hydroformylation process of mixed octene with the hydrogenation process of unreacted isooctene raw material, produces isooctane while producing isononanal, can make full use of raw materials and obtain two kinds of high added value The product is economically advantageous, simple in process, and suitable for industrial production.

Detailed ways

The present invention will be further described below in conjunction with embodiment.

In the present invention, a cobalt/phosphine oxide catalyst (or rhodium/phosphine oxide catalyst) is used in the hydroformylation process. By adding cobalt compound (or rhodium compound), phosphine oxide ligand and mixed octene and solvent into the reactor and feeding synthesis gas, the hydroformylation catalyst can be generated "in situ" and catalyzed mixed octene during the reaction process. Alkenes react with synthesis gas to produce isononanal.

In the present invention, a palladium/activated carbon (Pd/C) catalyst is used in the hydrogenation process.

The cobalt compound can be an inorganic salt of cobalt or an organic compound of cobalt, such as cobalt acetate, cobalt chloride, cobalt nitrate, dicobalt octacarbonyl, hydrogen cobalt tetracarbonyl, and the like. The compound of rhodium can be an inorganic salt of rhodium or an organic compound of rhodium, such as rhodium chloride, rhodium nitrate, rhodium dipolyacetate, hexarhodium hexadecacarbonyl, tetrarhodium dodecacarbonyl, etc. The phosphine oxide ligand may be triphenylphosphine oxide, tributylphosphine oxide, trioctylphosphine oxide, and the like.

The mixed octene used in the present invention is obtained by the oligomerization of n-butene, and mainly contains branched internal alkenes such as trimethylpentene, dimethylhexene and methylheptene.

The solvent used in the hydroformylation process of the present invention can be alcohol solvents such as methanol and ethanol, ester solvents such as ethyl acetate, ketone solvents such as acetone, ether solvents such as ether and ethylene glycol dimethyl ether, toluene, Aromatic solvents such as xylene, alkanes such as cyclohexane.

The synthesis gas used in the hydroformylation process of the present invention is a mixed gas of carbon monoxide (CO) and hydrogen (H ₂ ), and the ratio of CO/H ₂ is CO/H ₂ =1/1. According to the method of the present invention, the hydroformylation reaction is carried out at 160° C. and 8 MPa. During the reaction process, the synthesis gas is continuously supplied and the pressure of the synthesis gas is kept stable.

The hydrogen used in the hydrogenation process of the present invention is pure hydrogen. According to the method of the present invention, the hydrogenation reaction is carried out at 100-160° C. and 7-8 MPa. During the reaction process, hydrogen is continuously supplied and the pressure of the synthesis gas is kept stable.

Below is the embodiment of the present invention:

Example 1

In a stainless steel autoclave with an internal volume of 70ml, add 0.2345g of cobalt acetate (Co(CH ₃ COO) ₂ 4H ₂ O, product of Beijing Yili Fine Chemicals Co., Ltd.), 1.3130g of triphenylphosphine oxide (Ph ₃ PO , Beijing Hongyu Chemical Company), 15ml (10.5g) mixed octene and 5ml methanol (solvent). After sealing the reactor, fill the reactor with synthesis gas (CO/H ₂ =1/1) up to 3 MPa, and then release the pressure to normal pressure, repeating this three times to replace the air in the reactor. Heat the reactor to 160°C under normal pressure, then fill the reactor with synthesis gas (CO/H ₂ =1/1) up to 8MPa, and react at 160°C for 2.5 hours under stirring. During the reaction process, the synthesis gas is continuously supplied and Keep the pressure stable at 8MPa. After the hydroformylation reaction, stop the pressure supply, cool the reaction kettle to room temperature and reduce the pressure in the kettle to normal pressure, then take out the mixed liquid in the kettle and carry out vacuum distillation to obtain unreacted raw materials from the top of the distillation tower. Isooctene (trimethylpentene) and the product isononanal. The yield of the product isononanal is 51%.

Add 10 ml of isooctene (trimethylpentene) to a 50 ml stainless steel autoclave, and add 0.1023 g of palladium/activated carbon catalyst (5 wt% Pd/C, product of Strem Company, USA) catalyst. After the reactor is sealed, fill the reactor with pure hydrogen to 2MPa, and then release the pressure to normal pressure. Repeat this three times to replace the air in the reactor. Heat the reactor to 160°C under normal pressure, then fill the reactor with hydrogen to 7.5MPa, react at 160°C with stirring for 2.5 hours, supply hydrogen continuously during the reaction and keep the pressure stable at 7.5MPa. After the hydrogenation reaction, the reaction kettle was cooled to room temperature and the pressure in the kettle was reduced to normal pressure, and then the mixed liquid in the kettle was taken out for filtration and separation to obtain isooctane (trimethylpentane). The conversion of isooctene (trimethylpentene) was 100%. The reaction results are listed in Table 1.

Example 2

Except that the reaction temperature is 140° C., other operations are the same as in Example 1. The reaction results are listed in Table 1.

Example 3

Except that the reaction temperature is 120° C., other operations are the same as in Example 1. The reaction results are listed in Table 1.

Example 4

Except reaction temperature is 100 ℃, other operations are the same as embodiment 1. The reaction results are listed in Table 1.

Comparative example 1

Direct use of mixed octene feedstock for hydrogenation. Add 10 ml of mixed octene to a 50 ml stainless steel autoclave, and add 0.1023 g of palladium/activated carbon catalyst (5wt% Pd/C, product of Strem Company, USA) catalyst. After the reactor is sealed, fill the reactor with pure hydrogen to 2MPa, and then release the pressure to normal pressure, and repeat this three times to replace the air in the reactor. Heat the reactor to 160°C under normal pressure, then fill the reactor with hydrogen to 7.5MPa, react at 160°C with stirring for 2.5 hours, supply hydrogen continuously during the reaction and keep the pressure stable at 7.5MPa. After the hydrogenation reaction, the reaction kettle was cooled to room temperature and the pressure in the kettle was reduced to normal pressure, and then the mixed liquid in the kettle was taken out for filtration and separation to obtain isooctane (trimethylpentane). The conversion of isooctene (trimethylpentene) was 100%. The reaction results are listed in Table 1.

Table 1 Response example Isooctene (trimethylpentene) dosage 5wt% Pd/C dosage temperature(℃) Hydrogen pressure (MPa) time (h) Conversion rate of isooctene (%) Example 1 10ml 0.1023g 160 7.5 2.5 100 Example 2 10ml 0.1023g 140 7.5 2.5 100 Example 3 10ml 0.1023g 120 7.5 2.5 100 Example 4 10ml 0.1023g 100 7.5 2.5 97 Comparative example 1 Mixed octene 10ml 0.1023g 160 7.5 2.5 100

Claims (5)

1. A method for preparing isooctane, characterized in that: the method uses mixed octene as a raw material, and uses a cobalt catalyst or a rhodium catalyst to carry out hydroformylation under mild reaction conditions to obtain isononyl aldehyde. The unreacted isooctene is further hydrogenated to obtain isooctane, and the process steps are as follows: (1) Mixed octene hydroformylation reaction process: In the autoclave, add 0.2345g cobalt acetate, 1.3130g triphenylphosphine oxide ligand, 10.50g mixed octene 15ml and methanol solvent 5.0ml, the reactor is sealed Then put it in a heating furnace, replace the air in the reactor with CO/H ₂ =1/1 synthesis gas, heat the reactor to 160°C, and fill the reactor with CO/H ₂ =1/1 synthesis gas to 8MPa, under heat and pressure, stir and react for 2.5 hours, during the reaction process, continuously supply synthesis gas and keep the reaction pressure stable; (2) Separation process of hydroformylation product: After the hydroformylation reaction is over, take the reaction kettle out of the heating furnace, cool it to room temperature, reduce the pressure in the reaction kettle to normal pressure, open the lid of the kettle, take out the mixed Liquid, the mixed solution is subjected to vacuum distillation, separation catalyst and product isononanal and unreacted raw material isooctene; (3) Hydrogenation and separation process of unreacted raw material isooctene: add the isooctene obtained by distillation and separation into the reactor, add palladium/activated carbon catalyst, place the reactor in a heating furnace after sealing, and use pure hydrogen After replacing the air in the reactor, heat the reactor to 100-160°C, fill the reactor with pure hydrogen to 7.5MPa; stir and react under heating and pressure for 2.5 hours; during the reaction, continuously supply hydrogen and maintain the reaction The pressure is stable; after the hydrogenation reaction is completed, the reactor is taken out from the heating furnace and cooled to room temperature, the pressure in the reactor is reduced to normal pressure, the lid of the reactor is opened, and the mixed solution of the catalyst and the product is taken out and separated to obtain the iso octane. 2. The method for preparing isooctane according to claim 1, wherein the isooctene is trimethylpentene. 3. The method for preparing isooctane according to claim 1, wherein said isooctane is trimethylpentane. 4. The method for preparing isooctane according to claim 1, characterized in that: the reaction temperature in the step (3) is 100-160°C. 5. The method for preparing isooctane according to claim 1, characterized in that: the reaction pressure in the step (3) is 7.5Mpa.