CS254646B1 - A method for producing oxibenzine comprising a target. alkylmethyl ethers - Google Patents

Abstract

The production of oxybenzene containing tertiary alkyl methyl ethers freed from resinous substances from olefinic hydrocarbon mixtures and methanol is described. The process is carried out under energetically advantageous conditions on a combination of hydrogenation and acid catalyst in the presence of hydrogen-containing gases. The obtained product can be directly mixed into high-octane low- and unleaded motor gasolines.

Description

The present invention relates to the production of oxibenzin containing tertiary alkyl methyl ethers free of resinous substances, olefinic hydrocarbon mixtures and methanol, operating under energy-advantageous conditions on a combination of a hydrogenation and an acid catalyst in the presence of hydrogen-containing gases.

Low-grade and unleaded gasoline with high octane numbers are already unthinkable without oxygen derivatives of hydrocarbons, especially ethers and alcohols. These have very high mixed octane numbers and significantly improve the quality of gasoline at relatively low concentrations. The content of oxygen compounds is limited according to the oxygen concentration and for alcohols only 3 to 8% by volume of ether is permitted, especially the non-peroxide-forming types, ie primarily the target. alkyl methyl ethers, can reach concentrations up to 15% by volume without problems with engine modifications.

The production of ethers of this type is based on quaternary carbon isoolefins in the molecule, the simplest being isobutylene and two isoamylenes, 2-methylbutene -1 and -2. These olefins are a component of both thermal and catalytic cracking products in which their concentration ranges from 20 to 35% by weight. A significant impurity of said olefinic mixtures is dienes in concentrations of up to several% by weight. In addition to acyclic olefins, cyclopentenes are a typical component.

The reaction of isoolefins with methanol is equilibrium, and with increasing carbon number, the equilibrium is shifted to the feedstock side and the ether formation rate is lower for higher homologs in the temperature range up to 100 ° C. A common etherification catalyst is an acidic porous cation exchanger. e.g., a styrene-divinylbenzene copolymer. At temperatures between 50 and 90 ° C, residual dienes react to form apparent resins which give the product a brown color and are determined to be non-washed or washed resins. These are undesirable components of the product and must be removed by distillation. This increases the energy consumption of the process.

The present invention provides a solution for the production of oxibenzin containing resin-free tertiary alkyl methyl ethers starting from olefinic hydrocarbon mixtures and methanol. The process is characterized in that 0.9 to 1.5 moles of methanol are mixed with a feedstock containing 1 mol of tertiary olefins in an olefinic hydrocarbon mixture, heated to 50 to 90 ° C under a pressure of 1 to 4 MPa in the presence of 10 to 50 bar. volumes of hydrogen per volume of mixed feedstock in the presence of successive hydrogenation and etherification catalysts in at least two reaction stages, the volume ratio of hydrogenation and etherification zone being 1: 1 to 1: 5,

The olefinic hydrocarbon stream derived from catalytic cracking or thermal cracking of hydrocarbons and contains up to C ^, preferably C ₅ and / or C terci.olefiny _g at a concentration of 10 to 50% by weight. Catalytic reforming gas is most preferred as the hydrogenation gas. The catalysts for the hydrogenation stage are 0.1 to 0.5 wt. The palladium on gamma-alumina and the etherification catalyst is a porous styrene-divinylbenzene cation exchanger in the H ⁺ form with a specific surface area of up to 50 m / g.

The analysis of the process according to the invention shows above all the range of raw materials, operating conditions and types of catalysts. An advantage of the process according to the invention is that it is possible to use narrower or broader cuts containing mixtures of isoolefins in broader or narrower fractions from various hydrocarbon conversion processes. This produces oxibenzin in which the remaining components of the olefinic feedstock, the tert-alkylmethyl ether or a mixture thereof and the remainder of the methanol are present. By selecting the conditions in this range it is also possible to control the olefin content and thus the octane fraction number by the motor method, which is particularly important for unleaded gasoline.

In the example, the concrete results of the study of the production of oxibenzin from an olefinic feedstock and the properties of oxibenzin are shown.

Example

A mixed hydrogenation and etherification reaction mixture was prepared consisting of light pyrolysis gasoline boiling up to 65 ° C (LPB) predominantly containing C ₅ -carbons and 10% by weight. of methanol. In the mixture there was a molar ratio between reactive isoolefins with a target. carbon and methanol 1: 1.1. The LPB contained 2.75 wt. dienes.

Two catalytic layers were treated in a flow reactor, a hydrogenation catalyst (0.3 wt% palladium on gamma-alumina) and a cation exchanger in H ⁺ form with a specific surface area of 25 m / g.

In parallel, only the cation exchanger in the H ⁺ form was placed in the reactor. The conditions of both experiments are shown in Table 1.

Table 1 further presents products from both the combined and the etherification processes. A striking difference lies in the resin content, sample color and octane characteristics. The ether content (TAME) is approximately the same, indicating that there is no hydrogenation of the isoolefins with the target. carbon prior to their etherification. It can also be seen that the hydrogenation of cyclopentene to cyclopentane also takes place partially. This has a favorable effect on the octane number by the motor method of the product obtained by the combined process. and

Table 1

Working conditions and products for oxibenzine production.

Conditions:

medium nitrogen hydrogen pressure MPa 1.5 1.5 temperature ° C 80 80 assertion obj./obj. h 1 1 process etherification procedure according to Product quality: D ₂ 0 0,711 0.710 color Brown colorless non-washed resin mg / 100 ml 74.4 12.2 washed resin mg / 100 ml 71.8 3.6 % dieny wt. 1.30 0.39 content TAME% wt. 25.39 27.55 methanol content wt. 5.76 5.27 % etherifiable olefins wt. 10.5 10.0 % cyclopentene wt. 8.7 4.8 % cyclopentane wt. 18.0 21.7 Br-number g Br / 100 g 79.2 62.3 OČVM 97 99 OČMM 78 81

Similar results were obtained with light C ₄ to C ₂ light naphtha gasoline. olefins with quaternary carbon in the chain. Reaction rates dropped in the ratio of 2: 1: 0.5: 0.3 to C _? olefins.

Claims (4)

SUBJECT OF THE INVENTION 1.5 mol of methanol with 1 mole of tertiary olefins in an olefinic hydrocarbon mixture, heated to 50 to 90 ° C under 1 to 4 MPa in the presence of 10 to 50 volumes of hydrogen per volume of mixed feed in the presence of sequential hydrogenation and etherification catalysts in at least two reaction steps, the ratio of hydrogenation zone to etherification being in a volume ratio of 1: 1 to 1: 5. A process for preparing an oxibenzin comprising a target. resin-free alkyl methyl ethers of olefinic hydrocarbon mixtures and methanol, characterized in that from 0.9 to 2. Process according to claim 1, characterized in that the olefinic hydrocarbon mixture is derived from catalytic cracking or thermal cracking of hydrocarbons and contains up to C8 preferably and / or C8 tertiary olefins in a concentration of 10 to 50% by weight. 3. Process according to claim 1, characterized in that reformin gas is introduced as hydrogenation gas. g to 60 to 90% by volume of hydrogen in addition to saturated hydrocarbons. 4. A process according to any one of claims 1 to 3, wherein the hydrogenation catalyst comprises 0.1 to 0.5 wt. The palladium on gammaalumine and the etherification catalyst is styrene-divinylbenzene + 2 new porous cation exchange resin in H form with a specific surface area of 5 to 50 m / g.