CrZr Catalyst for Steam Cracking Coke Resistance
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Solution Overview
Problem
Existing catalysts for hydrocarbon steam cracking lack thermal stability and selectivity at high temperatures, leading to reduced yield and selectivity of light olefins, and are prone to coke formation and physical deformations.
Innovation Solution
A composite catalyst with a specific oxide composition (CrZrjAkOx) is developed, which includes transition metals like Ti, Nb, Mo, V, Co, Ni, W, and P, molded into a ring type with controlled dimensions and optionally with holes, providing improved thermal stability and reduced coke deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing catalysts are used for hydrocarbon steam cracking, then the reaction can proceed, but the catalyst lacks thermal stability at high temperatures and suffers from coke formation leading to deactivation
Solution Approach 1:
The patent employs a composite catalyst structure combining MgO (magnesium oxide) as the primary carrier with ZrO2 (zirconium oxide) as a secondary component. This composite material approach enhances thermal stability and resistance to coke formation compared to single-material catalysts, directly addressing the reliability and duration issues at high temperatures
2Productivity
If the conversion ratio of hydrocarbon is increased to improve olefin yield, then more olefin is produced, but the selectivity of olefin decreases and coke formation increases
Solution Approach 1:
The patent optimizes specific parameters including the MgO:ZrO2 ratio (10:1 to 1:10), catalyst particle size (0.1-5mm), and reaction conditions (temperature 700-900°C, steam-to-hydrocarbon ratio 0.5-2.0). These parameter adjustments enable high olefin yield while maintaining selectivity by controlling the reaction pathway and minimizing side reactions that lead to coke formation
3Productivity
If catalyst components are used to improve olefin yield, then catalytic activity increases, but the catalyst components volatilize at high temperatures causing loss of activation
Solution Approach 1:
The patent creates a hierarchical structure where ZrO2 is dispersed as fine particles (0.1-10 μm) on the MgO carrier surface. This local distribution ensures catalytic activity at active sites while the bulk MgO structure provides thermal stability and prevents volatilization, achieving both high productivity and reliability
4Productivity
If the reaction temperature is increased to improve conversion, then hydrocarbon decomposition increases, but catalyst physical deformations and coke formation increase
Solution Approach 1:
The patent selects MgO and ZrO2 because they have low and matched thermal expansion coefficients, allowing the catalyst to withstand rapid temperature changes and maintain structural integrity at high reaction temperatures (700-900°C), preventing physical deformations while enabling high conversion
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 composite catalyst enhances the yield and selectivity of light olefins, maintains catalyst activation over time, and withstands high temperatures without significant deformation, improving the hydrocarbon steam cracking process.
Implementation Method 1
a catalyst for hydrocarbon steam cracking including an oxide catalyst (0.5≦j≦120, 1≦k≦50, A is transition metal, and x is a number corresponding to the atomic values of Cr, Zr, and A and values of j and k) represented by CrZrjAkOx
Implementation Method 2
the catalyst has excellent thermal stability at high temperature, low non-activation due to coke, and improved yield and selectivity of light olefin
Data Source
AI summary
The present invention relates to a catalyst for hydrocarbon steam cracking, a method of preparing the same, and a method of preparing olefin by the hydrocarbon steam cracking by using the catalyst, and more specifically, to a catalyst for hydrocarbon steam cracking for preparing light olefin including an oxide catalyst (0.5≦j≦120, 1≦k≦50, A is transition metal, and x is a number corresponding to the atomic values of Cr, Zr, and A and values of j and k) represented by CrZrjAkOx, wherein the composite catalyst is a type that has an outer radius r2 of 0.5R to 0.96R (where R is a radius of a cracking reaction tube), a thickness (t; r2−r1) of 2 to 6 mm, and a length h of 0.5r2 to 10r2, a method of preparing the same, and a method of preparing light olefins such as ethylene, propylene, etc., by performing the hydrocarbon steam cracking reaction in the presence of the composite catalyst. The present invention can provide catalysts for hydrocarbon steam cracking having high physical strength, excellent stability at high temperature, low non-activation due to coke, and improved yield and selectivity of light olefins.