Hybrid Catalyst for C2-C3 Hydrocarbon Selectivity
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Solution Overview
Problem
Current processes for converting synthesis gas into C2 and C3 hydrocarbons often result in unacceptable levels of methanol, methane, and higher hydrocarbons, requiring costly separations and desiring catalysts with long lifetimes and minimal intermediate product streams.
Innovation Solution
A process involving a feedstream of hydrogen and carbon monoxide or carbon dioxide, reacted over a mixed catalyst bed comprising copper oxide, zinc oxide, and alumina, along with a non-metal modified molecular sieve, under specific temperature, pressure, and gas hourly space velocity conditions to produce a product mixture with high ethane and propane content and low methane and oxygenate levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional catalysts are used for converting synthesis gas into C2 and C3 hydrocarbons, then conversion occurs, but unacceptable levels of methanol, methane, and higher hydrocarbons are produced requiring costly separations
Solution Approach 1:
The patent employs a hybrid catalyst combining two distinct catalytic components: a methanol synthesis catalyst (Cu/ZnO/ZrO2) and a methanol conversion catalyst (zeolite or SAPO). This composite catalyst system enables selective production of C2-C3 hydrocarbons by coordinating the functions of both components, achieving high product selectivity and minimizing unwanted byproducts that would require expensive separations.
Solution Approach 2:
The catalytic process is divided into two sequential functions performed by separate catalyst components: first, the methanol synthesis catalyst converts synthesis gas to methanol, and second, the methanol conversion catalyst transforms methanol into C2-C3 hydrocarbons. This segmentation of the catalytic function allows each component to be optimized for its specific role, improving overall product selectivity.
2Duration of action of stationary object
If conventional catalysts are used, then conversion of synthesis gas occurs, but catalyst lifetime is limited and intermediate oxygenate formation requires additional separation steps
Solution Approach 1:
The hybrid catalyst combines a methanol synthesis catalyst with a methanol conversion catalyst in a single system, enabling direct conversion from synthesis gas to C2-C3 hydrocarbons without accumulating intermediate oxygenates. This integrated approach simplifies the overall process by eliminating the need for separate separation and conversion steps, reducing process complexity while extending catalyst lifetime.
3Productivity
If mixed metal oxide catalysts are used, then synthesis gas conversion occurs, but exact oxidation states vary making catalyst characterization inconsistent
Solution Approach 1:
The patent specifies a hybrid catalyst where the methanol synthesis component uses Cu/ZnO/ZrO2 with defined oxidation states (Cu(0), Cu(I), Cu(II), Zn(II), Zr(IV)) and the methanol conversion component uses well-characterized zeolite or SAPO structures. This composite approach maintains consistent catalyst characterization while achieving high conversion rates, as each component's oxidation state and structure are clearly defined and stable under reaction conditions.
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 process effectively converts synthesis gas into a product mixture with enhanced selectivity for C2 and C3 hydrocarbons, reducing unwanted byproducts and minimizing the need for expensive separations, while maintaining catalyst stability and avoiding intermediate oxygenate formation.
Implementation Method 1
A process involving a feedstream of hydrogen and carbon monoxide or carbon dioxide, reacted over a mixed catalyst bed comprising copper oxide, zinc oxide, and alumina, along with a non-metal modified molecular sieve
Data Source
AI summary
A feedstream comprising hydrogen and a gas selected from carbon monoxide, carbon dioxide, or a combination thereof is converted to a product mixture containing a combination of saturated and unsaturated two carbon atom and three carbon atom hydrocarbons via contact with a mixed catalyst comprising a mixed metal oxide catalyst selected from a copper oxide, copper oxide/zinc oxide, copper oxide/alumina, copper oxide/zinc oxide/alumina catalyst, a zinc oxide/chromium oxide catalyst, or a combination thereof, in admixture with a molecular sieve catalyst having a CHA, AEI, AEL, AFI, BEA, or DDR framework type, or a combination of such molecular sieves. Exemplary molecular sieve catalysts include SAPO-34, SAPO-18, SAPO-5, and Beta. Advantages include reduced production of C1 hydrocarbons, C4 and higher hydrocarbons, or both; long catalyst lifetimes; desirable conversions; and desirable proportions of C2 and C3 paraffins.