Binder-Free ZSM-5 Zeolite via Vapor-Solid Crystallization

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Solution Overview

Problem

Existing methods for producing ZSM-5 zeolites in small crystal size are complex, generate waste, and often require initial zeolite powder and binders, limiting their application due to large crystal size and diffusional limitations.

Innovation Solution

A process using diatomite or carbon white as silica sources, aluminum oxides, a seed crystal orienting agent, and extrusion aids for kneading and shaping, followed by vapor-solid phase crystallization at controlled temperatures to produce binder-free ZSM-5 zeolites with submicron particle sizes, eliminating the need for inert binders and simplifying the preparation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If binder is added in the shaping process, then the zeolites can be shaped and handled conveniently, but the effective surface area is reduced and diffusional limitation is introduced

Engineering Contradiction:

Improvehandling convenienceVSAvoideffective surface area

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The invention extracts and eliminates the binder component from the shaping process. By using extrusion aids instead of traditional binders, the zeolite particles can be shaped without inert materials that would reduce effective surface area and create diffusional limitations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces extrusion aids as intermediary substances that facilitate shaping without the negative effects of traditional binders. These aids enable the forming process while maintaining zeolite particle integrity and avoiding surface area loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If initial zeolite powder is prepared and mixed with binder for shaping, then binder-free zeolites can be produced, but the preparation process becomes complex and waste is generated

Engineering Contradiction:

Improvebinder-free product qualityVSAvoidpreparation process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the shaping and crystallization steps into a unified process. By using extrusion aids during shaping followed by vapor-solid phase crystallization, the process eliminates the need for separate binder removal and washing steps, reducing complexity and waste generation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The vapor-solid phase crystallization process allows the shaped precursor to self-transform into binder-free zeolite crystals. The extrusion aids decompose during crystallization, and the zeolite structure forms autonomously without requiring additional processing steps for binder removal.

Inventive Principle:

Principle #25Self-service

3Productivity

If zeolites in small crystal size are produced, then catalytic activity and selectivity are improved, but the zeolites are difficult to recover and easily inactivate and aggregate

Engineering Contradiction:

Improvecatalytic activityVSAvoidstability and recoverability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention creates a composite structure where small crystal size zeolites are formed within a shaped matrix. The extrusion aid framework provides structural support that prevents aggregation of small crystals while maintaining their high surface area and catalytic activity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The extrusion process creates shaped particles with curved, integrated structures that accommodate small zeolite crystals. This shaping prevents flat surface aggregation and improves recoverability while maintaining small crystal size benefits.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 method results in a simpler, waste-free process that produces ZSM-5 zeolites with enhanced catalytic properties and improved strength due to interwoven crystal structures, overcoming the limitations of larger crystal sizes and diffusional issues.

Implementation Method 1

converting to binder-free ZSM-5 shaped zeolites in small crystal size by vapor-solid phase crystallization with organic amine and water vapor

Methodology Applied

Scientific EffectVapor-solid phase crystallization: Crystallisation

Implementation Method 2

adding a seed crystal orienting agent... wherein said seed crystal orienting agent is obtained by aging the mixture

Methodology Applied

Scientific EffectSeed crystal orientation: Nucleation

Data Source

PatentUS7601330B2Process for producing binder-free ZSM-5 zeolite in small crystal size

Publication Date: 2009.10.13 CHINA PETROLEUM & CHEMICAL CORP

AI summary

The present invention relates to a process for producing a binder-free ZSM-5 zeolite in small crystal size. The invention is primarily used for solving the problems in the practical application, e.g., the zeolite powder is difficult to be recovered and easily inactivates and aggregates, and the addition of the binder in the shaping process will result in the reduction of effective surface areas and introduce the diffusional limitation. Said problems are better solved in the present invention by using diatomite or silica aerogel as the main starting material, adding a seed crystal orienting agent, a silica sol and sodium silicate for kneading and shaping, and then converting to integrative ZSM-5 in small crystal size by vapor-solid phase crystallization with organic amine and water vapor. Said process can be used in the industrial preparation of ZSM-5 molecular sieve catalyst in small crystal size.