Arco Chemical Technology, L.p.

Other

Guy L Crocco

John G Zajacek

Robert James Saxton

John C Jubin, Jr

Kanthi S Wijesekera

Haven S Kesling, Jr

David W Leyshon

Te Chang

Wilfred F Shum

A titanium-containing molecular sieve which has been used as an oxidation catalyst is regenerated to provide a level of performance comparable to that of freshly prepared catalyst by heating at less than 400.degree. C. in the presence of molecular oxygen. The same batch of catalyst thus may be used over an extended period of time in a continuous epoxidation process by periodic practice of the aforedescribed reactivation method.

Regeneration of a titanium-containing molecular sieve

A titanium-containing molecular sieve which has been used as an oxidation catalyst is regenerated to provide a level of performance comparable to that of freshly prepared catalyst by heating in the presence of a gas stream comprised of less than 5 volume percent molecular oxygen. The regeneration temperature may be in the range of from 150.degree. C. to 700.degree. C. The same batch of catalyst thus may be used over an extended period of time in a continuous epoxidation process by periodic practice of the aforedescribed reactivation method.

A crystalline molecular sieve having a framework structure isomorphous with zeolite beta and containing Si and Ti, but essentially no framework Al, usefully catalyzes olefin epoxidation wherein hydrogen peroxide is the oxidant.

Tiatanium containing molecular sieve having a zelite beta structure

Epoxides are produced by an integrated process involving molecular oxygen oxidation of a secondary alcohol, separation of the ketone co-product, and epoxidation of an olefin using the ketone-free oxidation product in the presence of a titanium silicalite catalyst and a methanol-containing diluent wherein methanol recovered from the epoxidation product mixture serves as a source of methanol in the epoxidation step.

Integrated process for epoxidation

Epoxidation process

An as-synthesized zeolite having titanium substituted in its lattice framework and containing an organic template such as a quaternary ammonium salt may be activated for use as a catalyst by treating said as-synthesized zeolite with ozone. At least partial removal and/or reaction of the organic template is accomplished even at moderate temperatures, in contrast to conventional calcination techniques which require the use of significantly higher activation temperatures.

Activation of as-synthesized titanium-containing zeolites

The selectivity of an olefin epoxidation process catalyzed by titanium silicalite is improved by performing the epoxidation in the presence of minor amounts of nonbasic salts such as lithium chloride, sodium nitrate, potassium sulfate, and ammonium dihydrogen phosphate. For example, when hydrogen peroxide is reacted with propylene to form propylene oxide, non-selective ring-opening reactions of the propylene oxide are suppressed when low concentrations of a nonbasic salt are added to the hydrogen peroxide feed.

Process for titanium silicalite-catalyzed epoxidation

A crystalline molecular sieve having a framework structure isomorphous with zeolite beta and containing Si and Ti, but essentially no framework Al, usefully catalyzes olefin epoxidation wherein hydrogen peroxide or an organic hydroperoxide is utilized as the oxidizing agent.

An integrated process for producing cyclohexanone oxime, a caprolactam precursor, is provided wherein isopropanol is utilized to generate the hydrogen peroxide oxidizing agent. The acetone produced as a co-product is recycled back to the secondary alcohol by hydrogenation. Ammoximation of cyclohexanone is performed in the presence of water and an alcohol other than isopropanol such as methanol or t-butyl alcohol.

Integrated process for cyclohexanone oxime production

In an epoxidation process wherein an olefin is reacted with hydrogen peroxide in the presence of a titanium-containing molecular sieve catalyst and a salt, the tendency of the catalyst to produce greater quantities of oxygen as it ages due to non-selective decomposition of the hydrogen peroxide may be counteracted by the addition of a chelating agent bearing hydroxyl, carboxyl, amino, and/or phosphoryl groups. The use of such a chelating agent enables selectivity to epoxide to be maintained at a desirably high level for a prolonged period of time in a continuous epoxidation unit.

Epoxidation Process

Method of making a titanium-containing molecular sieve

Epoxides are produced by an integrated process involving molecular oxygen oxidation of a secondary alcohol, separation of the ketone by-product, and epoxidation of an olefin in the presence of a titanium silicalite catalyst and a diluent, wherein a crude alcohol stream obtained by removing epoxide from the epoxidation product mixture serves as the diluent. Despite use of the crude alcohol stream, which typically comprises water, organic acids and glycols, high selectivities to epoxides such as propylene oxide are realized.

Crystalline aluminosilicates such as zeolite beta may be readily dealuminated using organic sulfonic acids such as methanesulfonic acid to provide useful catalysts or catalyst precursors. A high degree of aluminum removal with minimal loss of crystallinity is possible even when an organic template is not present in the starting aluminosilicate.

Dealumination of aluminosilicates

An integrated process for producing cyclohexanone oxime, a caprolactam precursor, is provided wherein a secondary alcohol is utilized to generate the hydrogen peroxide oxidizing agent and as a reaction medium for ammoximation. The ketone produced as a co-product is recycled back to the secondary alcohol by hydrogenation.

Olefins are epoxidized by hydrogen peroxide in the presence of a modified titanium-containing molecular sieve having a framework structure isomorphous with zeolite beta and comprised of Si, Ti, and Al. The molecular sieve is modified by substituting the aluminum-associated cationic sites with ammonium, alkali metal, or alkaline earth cations instead of protons.

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Wilmington, DE, United States of America

Guy L Crocco