Spinel Catalyst for Butene Dehydrogenation Stability
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Solution Overview
Problem
Current catalysts for the oxidative dehydrogenation of butene to butadiene suffer from low catalytic activity, selectivity, and stability, with carbon deposits forming during reaction, leading to decreased performance over time.
Innovation Solution
A catalyst with the general structural formula ZnaAlbMcFeeOf.Z(α-Fe2O3) is developed, incorporating specific elements like Be, Mg, Ca, Sr, Mn, Ba, Cu, Co, and Ni, with a spinel crystal phase and α-Fe2O3, optimized through a preparation process involving mixed salt solutions, precipitation, aging, drying, and calcination, enhancing surface area and acid site distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional ferrite-based catalysts are used for oxidative dehydrogenation of butene to butadiene, then mild reaction conditions and high catalytic activity are achieved, but catalyst stability is poor and performance degrades quickly
Solution Approach 1:
The patent employs composite spinel catalysts with multiple metal elements (Mg, Al, Fe, Cr, Mn, Co, Ni, Cu, Zn, Ca, Sr, Ba, Be) combined in specific ratios to create a composite material structure. This composite approach integrates the advantages of different metal oxides: MgO provides basic sites for butene activation, Al2O3 enhances structural stability, Cr2O3 improves resistance to carbon deposition, and other metals contribute to catalytic activity and selectivity. The synergistic effect of these components resolves the contradiction between high catalytic activity and long-term stability.
Solution Approach 2:
The patent systematically optimizes multiple parameters including metal composition ratios (a, b, c, d, e, f in the formula), calcination temperature (500-900°C), calcination time (3-72 hours), and preparation method parameters. By changing these parameters, the catalyst achieves maximum catalytic activity while maintaining structural stability and resistance to deactivation. The specific parameter range of 0.01≤a≤1.0, 0.5≤b≤2.0, 0.1≤c≤1.0, and a+b+c=3.0 represents optimized parameter changes to balance activity and stability.
2Productivity
If catalysts are used for extended operation periods, then continuous production is maintained, but carbon deposits accumulate on the catalyst surface leading to decreased catalytic activity
Solution Approach 1:
The patent converts the harmful effect of carbon deposition into a beneficial feature by incorporating Cr2O3 and other metal oxides that promote oxygen mobility and facilitate in-situ oxidation of carbon deposits. The Cr3+ ions in the spinel structure create oxygen vacancies that enhance oxygen diffusion, allowing carbon deposits to be oxidized and removed during reaction conditions. This transforms the harmful carbon accumulation into a self-cleaning process, maintaining catalytic activity during extended operation.
Solution Approach 2:
The patent enables continuous catalytic action by designing a catalyst that maintains active sites throughout extended operation. The spinel structure provides a stable framework that prevents sintering and maintains surface area, while the multiple metal components ensure continuous availability of active sites for butene activation and butadiene formation. The catalyst structure allows continuous reaction without significant loss of activity over time.
3Productivity
If catalyst selectivity is improved to increase butadiene yield, then desired product formation is enhanced, but catalyst complexity increases
Solution Approach 1:
The patent applies local quality by creating specific functional regions within the catalyst structure. Different metal elements are positioned in the spinel lattice to perform specific functions: Mg and Al provide structural framework and basic sites, Cr creates oxygen vacancies for carbon removal, Mn and Co enhance oxidation activity, and Cu and Zn improve selectivity. This localized functional distribution within the unified spinel structure achieves high butadiene yield without excessive overall 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 exhibits high selectivity and stability, maintaining high conversion and yield of butadiene with a catalyst life exceeding 6,000 hours, compared to previous catalysts which degrade significantly within 1,800 hours.
Implementation Method 1
Catalyst for the oxidative dehydrogenation of butene to butadiene
Implementation Method 2
preparation process involving mixed salt solutions, precipitation, aging, drying, and calcination
Data Source
AI summary
The present disclosure provides a catalyst for oxidative dehydrogenation of butene to butadiene, comprising at least one compound of formula ZnaAlbMcFeeOf.Z(α-Fe2O3), wherein M is at least one element chosen from Be, Mg, Ca, Sr, Mn, Ba, Cu, Co, and Ni, Z represents the percentage by weight of α-Fe2O3 in the catalyst and ranges from 10% to 70%. Also provided herein is a process of preparing said catalyst and the use of said catalyst in an oxidative dehydrogenation of butene to butadiene processes.