Method for preparing isobutene through direct hydration method

Abstract

The invention discloses a method for preparing isobutene through a direct hydration method. The method for preparing isobutene through separation is carried out by adopting strongly acidic cation exchange resin as a catalyst to separate the isobutene from a C4 mixture through two steps of: firstly, mixing isobutene in the C4 mixture to generate tertiary butyl alcohol through hydration; and secondly, dehydrolyzing the tertiary butyl alcohol to obtain high-purity isobutene. Since the porous strongly acidic cation exchange resin is adopted as the catalyst which has very high selectivity and low possibility of reaction with other alkenes, the purity of the tertiary butyl alcohol is high, and the purity of the isobutene is also high. Gas-phase isobutene is guaranteed to be condensed through circulating water, therefore the operating pressure is generally 0.35-0.4MPa (gauge pressure). The method disclosed by the invention has the advantages of reasonable process and simple preparation, thereby being a simplest, most convenient and ideal method for preparing isobutene.

Description

technical field [0001] The invention relates to a chemical product, in particular to a technology for preparing isobutene by direct hydration, which is suitable for producing isobutene. Background technique [0002] (CH3)2C=CH2 is also known as 2-methylpropene. Flammable and explosive gas (explosive limit 1.7% to 9.0% volume), boiling point -6.90°C, critical temperature 144.75°C, critical pressure 4.00MPa. Industrially, isobutene is almost always obtained from refinery gas and cracking C4 fractions (see C4 fractions). The content of isobutene in refinery gas is generally 5% to 12%, and the content of cracked C4 fraction is generally 20% to 30%. In a few cases, it is obtained by the catalytic dehydrogenation of isobutane using a chromia-alumina catalyst. When propylene and isobutane are used as raw materials to produce propylene oxide by co-oxidation, isobutene is its co-product. [0003] Separation of isobutene from the C4 fraction is usually carried out after first sepa...

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Problems solved by technology

[0005] The problem to be solved by the present invention is to overcome the deficiencies of the prior art. The prior art is that isobutanol is dehydrated at 360 to 370° C. and 0.304 to 0.405 MPa (3 to 4 atm) (the catalyst is activated alumina) to obtain 86%-87% crude isobutene, and then refined isobutene can be obtained after rectification and removal of acetaldehyde, ether, and organic acids. The original method has high reaction temperature, high energy consumption, and single product

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