Epoxidation Catalyst with Lead and Bismuth Modifiers
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Solution Overview
Problem
Current direct epoxidation catalysts for olefins with oxygen and hydrogen often produce non-selective byproducts such as glycols or alkane byproducts, which reduce the efficiency of the epoxidation process.
Innovation Solution
A catalyst comprising a noble metal, lead, bismuth, and a titanium or vanadium zeolite is used in the epoxidation process, which significantly reduces alkane byproduct formation by promoting a more selective reaction of olefins with oxygen and hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional direct epoxidation catalysts (noble metal and titanosilicate) are used, then the epoxidation reaction can proceed, but non-selective byproducts such as glycols and alkane are formed
Solution Approach 1:
The patent modifies the catalyst composition by incorporating lead and bismuth modifiers alongside the noble metal and titanosilicate components. These compositional parameter changes selectively suppress the hydrogenation and ring-opening pathways while maintaining the epoxidation function, thereby reducing alkane and glycol byproducts
Solution Approach 2:
The invention employs a composite catalyst system combining multiple components: noble metal (for oxygen activation), titanosilicate (for epoxidation activity), lead (for suppressing hydrogenation), and bismuth (for suppressing ring-opening). This multi-component composite achieves superior selectivity compared to conventional two-component catalysts
2Reliability
If more conventional catalyst components are added to improve selectivity, then byproduct formation decreases, but catalyst complexity increases
Solution Approach 1:
The patent optimizes the compositional parameters by incorporating specific modifiers (lead and bismuth) at controlled levels. This targeted parameter modification achieves enhanced selectivity without requiring complete redesign of the catalyst system, balancing performance improvement with manageable complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The catalyst system enhances the selectivity of the epoxidation process by minimizing the production of non-selective byproducts, thereby improving the yield of desired epoxides like propylene oxide.
Implementation Method 1
the catalyst comprises a noble metal and a titanosilicate. For example, JP 4-352771 discloses the formation of propylene oxide from propylene, oxygen, and hydrogen using a catalyst containing a Group VIII metal such as palladium on a crystalline titanosilicate. The Group VIII metal is believed to promote the reaction of oxygen and hydrogen to form a hydrogen peroxide in situ oxidizing agent.
Implementation Method 2
In this process, it is believed that oxygen and hydrogen react in situ to form an oxidizing agent. Many different catalysts have been proposed for use in the direct epoxidation process.
Implementation Method 3
U.S. Pat. No. 6,005,123 teaches the use of phosphorus, sulfur, selenium or arsenic modifiers such as triphenylphosphine or benzothiophene to decrease the production of propane. U.S. Pat. No. 7,026,492 discloses that the presence of carbon monoxide, methylacetylene, and/or propadiene modifier gives significantly reduced alkane byproduct. In addition, co-pending U.S. Pat. Appl. Ser. No. 11/489,086 discloses that the use of a lead-modified palladium-containing titanium or vanadium zeolite reduces alkane byproduct formation.
Data Source
AI summary
Catalysts useful for the direct epoxidation of olefins are disclosed. The catalysts comprise a noble metal, lead, bismuth, and a titanium or vanadium zeolite. The noble metal, lead, and bismuth may be supported on the titanium or vanadium zeolite. The catalyst may also be a mixture comprising the titanium or vanadium zeolite and a supported catalyst comprising the noble metal, lead, bismuth, and a carrier. The invention includes a process for producing an epoxide comprising reacting an olefin, hydrogen and oxygen in the presence of the catalyst. The process results in significantly reduced alkane byproduct formed by the hydrogenation of olefin.