Dewaxing Catalyst Composite Binder System
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Solution Overview
Problem
Conventional dewaxing catalysts are susceptible to poisoning by sulfur and nitrogen contaminants and face challenges in maintaining mechanical strength while maximizing dewaxing activity, especially when using low surface area binders which result in low crush strength and high particle density.
Innovation Solution
A supported catalyst comprising a zeolite with a silica to alumina molar ratio of 500 or less, combined with a large crystallite size first metal oxide binder and a small crystallite size second metal oxide binder, providing a balance between catalytic activity and mechanical strength, and optionally including a metal hydrogenation component for isomerization dewaxing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a low surface area binder is used to increase access to zeolite active sites and improve catalytic activity, then the dewaxing activity is improved, but the crush strength decreases and particle density increases
Solution Approach 1:
The patent combines two different binder types with complementary properties: a low surface area binder (first metal oxide binder with crystallite size > 200 Å) to provide mechanical strength and structural stability, and a high surface area binder (second metal oxide binder with crystallite size < 100 Å) to increase access to zeolite active sites. This merging of binder types resolves the contradiction by having each binder fulfill its specialized function without compromising the other.
Solution Approach 2:
The catalyst employs a composite binder system consisting of multiple metal oxide binders with different crystallite sizes and surface areas. The composite structure allows the catalyst to simultaneously achieve high catalytic activity (through increased active site accessibility) and adequate mechanical strength (through the structural support of the low surface area binder), eliminating the need to choose between these competing requirements.
2Productivity
If the silica to alumina ratio of zeolite is reduced to increase catalytic activity, then the dewaxing performance is improved, but the mechanical strength of the catalyst decreases
Solution Approach 1:
The patent modifies the zeolite composition parameter (silica to alumina ratio) to achieve optimal catalytic activity while compensating for the resulting mechanical strength deficiency through careful selection and proportioning of the binder system. By adjusting the binder crystallite sizes and ratios, the catalyst maintains both high dewaxing performance and adequate mechanical strength despite using zeolite with lower silica to alumina ratio.
3Productivity
If conventional dewaxing catalysts are used to convert long chain normal paraffins, then the low temperature properties are improved, but the catalyst is susceptible to poisoning by sulfur and nitrogen contaminants
Solution Approach 1:
The patent introduces a protective binder system that acts as an intermediary between the vulnerable zeolite active sites and the harmful sulfur and nitrogen contaminants in the feedstock. The binder matrix provides a protective environment that reduces direct contact between contaminants and active sites, thereby decreasing catalyst poisoning while maintaining effective dewaxing conversion of long chain normal paraffins.
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 achieves improved dewaxing performance with enhanced mechanical strength and reduced particle density, maintaining high catalytic activity and commercial viability, as demonstrated by its effectiveness in dewaxing wax-containing hydrocarbon feeds under various conditions.
Implementation Method 1
Catalytic dewaxing involves chemically converting the hydrocarbons leading to unfavorable low temperature properties to hydrocarbons having more favorable low temperature properties. Catalysts that isomerize do not normally result in significant boiling point conversion.
Implementation Method 2
Catalytic dewaxing may be accomplished using catalysts that function primarily by cracking waxes to lower boiling products
Implementation Method 3
To ensure adequate mechanical strength for use in a dewaxing reactor, such zeolite catalysts are generally combined with an inorganic oxide binder, such as alumina
Implementation Method 4
Catalytic dewaxing is a process for converting these long chain normal paraffins and slightly branched paraffins to molecules having improved low temperature properties
Data Source
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AI summary
A supported catalyst comprises a zeolite having a silica to alumina molar ratio of 500 or less, a first metal oxide binder having a crystallite size greater than 200 Å and a second metal oxide binder having a crystallite size less than 100 Å, wherein the second metal oxide binder is present in an amount less than 15 wt% of the total weight of the catalyst.