Cracking Catalyst for Butenes to Light Olefins
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Solution Overview
Problem
Current processes for producing light olefins like ethylene and propylene, such as thermal cracking and fluid catalytic cracking, result in significant yields of lower-value C4 streams containing mixed butenes and butanes, limiting the production of higher-value propylene and ethylene.
Innovation Solution
A cracking catalyst comprising zeolite particles with a high silica-to-alumina molar ratio and an alumina binder, impregnated with iron or nickel oxide, is used to convert mixed butenes into propylene and ethylene through catalytic cracking, potentially combined with metathesis processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal cracking or fluid catalytic cracking is used to produce light olefins, then ethylene and propylene can be produced, but significant amounts of lower-value C4 streams (mixed butenes and butanes) are also produced
Solution Approach 1:
The patent changes the chemical parameters of the catalyst by using zeolite with high silica-to-alumina ratio (≥500) and specific pore structure, along with controlled impregnation of transition metals (Fe, Ni, Co, Mn, Zn) to optimize the catalytic activity for C-C bond scission. This parameter optimization enables selective cracking that favors light olefin production while minimizing C4 byproducts
Solution Approach 2:
The patent creates a composite catalyst system combining zeolite support with impregnated transition metals. The zeolite provides the acidic sites and pore structure, while the transition metals enhance the cracking activity and selectivity. This composite approach allows simultaneous improvement of light olefin yield and reduction of C4 side products
2Productivity
If conventional cracking catalysts are used, then the cracking process can proceed, but the catalytic activity is insufficient to maximize propylene and ethylene yields
Solution Approach 1:
The patent optimizes catalyst parameters by controlling the silica-to-alumina ratio (≥500), pore size (0.3-0.6 nm), and impregnation amount of transition metals (0.1-5 wt%). These parameter changes enhance the density and strength of acidic sites, improving catalytic activity and stability for maximum light olefin production
Solution Approach 2:
The patent utilizes zeolite with specifically controlled pore dimensions (0.3-0.6 nm) to enhance catalytic activity. The porous structure provides high surface area and shape-selective pathways that favor the formation and diffusion of light olefins (ethylene and propylene), thereby maximizing yield while maintaining high catalytic activity through increased active site accessibility
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
This approach increases the yield of propylene and ethylene from mixed butenes compared to conventional catalysts, reducing the formation of side products and enhancing the catalytic activity of the zeolite particles.
Implementation Method 1
The cracking catalyst of the present disclosure includes zeolite particles comprising a medium pore zeolite and an aluminum binder. The cracking catalyst further comprises iron oxide, nickel oxide, or iron oxide and nickel oxide impregnated onto the surfaces of the zeolite particles.
Implementation Method 2
The medium pore zeolite has a high silica to alumina molar ratio of greater than or equal to 500 and very low phosphorous content, such as less than or equal to 1000 parts per million by weight.
Data Source
AI summary
A process for cracking olefins to produce propylene, ethylene, or both, includes providing a feed stream that includes mixed butenes and contacting the feed stream with a cracking catalyst at reaction conditions that cause at least a portion of the mixed butenes in the feed stream to react to form propylene, ethylene, or both. The cracking catalyst includes zeolite particles formed from shape selective zeolite particles and an alumina binder. The cracking catalyst further includes at least one transition metal oxide impregnated onto the zeolite particles, where the at least one transition metal oxide can be iron oxide, nickel oxide, or a combinations of these. The cracking catalyst with the iron oxide, nickel oxide, or both increases conversion of mixed butenes to propylene, ethylene, or both alone or in combination with a metathesis upstream of the cracking catalyst, as compared to conventional cracking catalysts.