Solid Acid Alkylation Catalyst via Seed-Assisted, Low-Toxicity MWW Synthesis
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Solution Overview
Problem
Existing alkylation catalysts, such as L-acid and B-acid catalysts, face issues like environmental pollution, high costs, catalyst deactivation, and the need for expensive and toxic template agents in synthesizing MWW-structured molecular sieves, which affect the stability and efficiency of alkylation reactions.
Innovation Solution
A method for synthesizing a solid acid alkylation catalyst using a crystal seed and two template agents, including cyclohexylamine and low-toxicity aliphatic amines, to form a MWW-structured molecular sieve with interlayer hydrogen bonding, avoiding hexamethyleneimine, piperidine, or homopiperazine, and enhancing catalyst stability and activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional template agents (hexamethyleneimine, piperidine, homopiperazine) are used for synthesizing MWW-structured molecular sieves, then the molecular sieve structure can be formed, but the synthesis cost increases and environmental pollution worsens due to toxicity and expense
Solution Approach 1:
The patent replaces expensive and toxic template agents with cheap, non-toxic alternatives like quaternary ammonium salts and organic acids that can be easily disposed of or degraded, eliminating environmental pollution while maintaining the molecular sieve structure formation capability
Solution Approach 2:
The patent introduces intermediate substances (quaternary ammonium salts and organic acids) as alternative template agents that mediate the formation of MWW-structured molecular sieves without the harmful effects of traditional template agents, achieving structure formation through different chemical mechanisms
2Productivity
If L-acid catalysts (anhydrous AlCl3) are used for alkylation reactions, then catalytic activity is good and technology is mature, but aluminum-containing waste liquid is generated and side reactions increase
Solution Approach 1:
The patent changes the fundamental parameter of catalyst phase from liquid (anhydrous AlCl3) to solid (MWW-structured molecular sieve), transforming the catalyst into a reusable solid material that eliminates waste liquid generation while maintaining catalytic activity for alkylation reactions
Solution Approach 2:
The patent replaces the liquid-phase chemical catalyst system with a solid-phase catalyst system, substituting the mechanism of catalysis while achieving elimination of harmful waste liquid byproducts
3Adaptability or versatility
If B-acid catalysts (HF, H2SO4) are used for alkylation reactions, then the catalysts work for long chain olefins, but strong corrosiveness requires high material requirements and emits various wastes
Solution Approach 1:
The patent changes the catalyst from liquid acid phase to solid phase with different chemical properties, eliminating corrosiveness while maintaining the ability to catalyze alkylation reactions of long chain olefins through solid acid catalysis mechanisms
Solution Approach 2:
The patent replaces expensive corrosion-resistant materials required for B-acid catalysts with ordinary materials that can contain solid acid catalysts, significantly reducing equipment cost and eliminating corrosive waste emissions
4Speed
If 12-membered ring macroporous molecular sieves are used, then internal channel diffusion performance is strong, but catalyst deactivation occurs due to blockage of internal channels by macromolecules
Solution Approach 1:
The patent segments the molecular sieve structure into hierarchical pore systems with both micropores and mesopores, creating multiple diffusion pathways that prevent macromolecule blockage while maintaining fast diffusion performance through the mesoporous network
Solution Approach 2:
The patent introduces a new dimensional aspect to the pore structure by creating hierarchical porosity with mesopores (50-500 nm) in addition to micropores, adding a mesoscale dimension that provides alternative diffusion routes for macromolecules and prevents channel blockage
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 alkylation catalytic activity and product selectivity, reducing costs and environmental impact while improving the operability and stability of MWW-structured molecular sieves in alkylation reactions.
Implementation Method 1
mixing an aluminum source, water, an alkali source, a template agent, a silicon source, and a crystal seed to form a gel, and subjecting the gel to a crystallization reaction to obtain a MWW-structured molecular sieve
Implementation Method 2
a MWW-structured molecular sieve with interlayer hydrogen bonding
Data Source
AI summary
A solid acid alkylation catalyst, and a preparation method therefor and a use thereof. The preparation method comprises the following steps: S1, mixing an aluminum source, water, an alkali source, a template agent, a silicon source and a seed crystal to form gel, and carrying out a crystallization reaction to obtain a molecular sieve having an MWW structure, wherein the template agent is composed of a main template agent and an auxiliary template agent in a molar ratio of 0.5-20:1; S2, roasting the molecular sieve having the MWW structure obtained in S1 to remove the template agent, then carrying out ammonium exchange, and roasting again to obtain an H-type molecular sieve; and S3, mixing the H-type molecular sieve obtained in S2 with an inorganic oxide and a nitric acid solution, and performing kneading and shaping to obtain the solid acid alkylation catalyst. By using the method for synergistically assisting crystallization by a seed crystal and two template agents, a molecular sieve having an MWW structure is directly synthesized without using hexamethyleneimine, piperidine and homopiperazine, and the solid acid alkylation catalyst is further obtained.