IZM-2 Zeolite Catalyst Heat Treatment for Isomerization Selectivity
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Solution Overview
Problem
Middle distillate bases produced from renewable sources or low-temperature Fischer-Tropsch synthesis often have insufficient cold properties due to high molecular weight linear or weakly branched paraffins, leading to freezing issues at low temperatures, and existing dewaxing methods are costly and inefficient.
Innovation Solution
A bifunctional catalyst comprising IZM-2 zeolite and a noble metal from group VIII, such as platinum, is prepared using a specific process involving shaping, metal deposition, and heat treatment with a gas mixture containing oxygen, water, and chlorine to enhance isomerization selectivity and activity, reducing hydrogenolyzing activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If selective cracking of long linear paraffinic chains is performed using ZSM-5 zeolite, then pour point values are reduced, but significant quantities of lower molecular weight products are formed which considerably reduces the yield of desired products
Solution Approach 1:
The invention changes the pore size parameter of the zeolite from 10MR (ZSM-5) to 12MR (beta zeolite), which fundamentally alters the shape selectivity and reaction pathway. This parameter change allows the catalyst to isomerize long paraffinic chains without cracking them into low molecular weight products, thus reducing pour point while maintaining high yield of desired middle distillate products
Solution Approach 2:
The invention applies a specific coating composition with controlled properties (silica-alumina gel with specific SiO2/Al2O3 ratio and pore structure) to the zeolite crystals. This creates local quality differences where the coating provides shape selectivity for isomerization while the bulk beta zeolite provides the active sites, preventing unwanted cracking reactions
2Temperature
If hydroisomerization processes are performed to isomerize long linear paraffins, then cold stability is improved, but catalyst selectivity must be precisely controlled to minimize cracking
Solution Approach 1:
The invention changes the zeolite structure parameter to beta zeolite with 12MR pores, which provides inherent shape selectivity that promotes isomerization over cracking. This structural parameter change ensures high catalyst selectivity without requiring precise control of operating conditions, reliably improving cold stability
Solution Approach 2:
The invention creates a composite catalyst system combining beta zeolite crystals with a silica-alumina coating layer. This composite structure integrates the isomerization activity of beta zeolite with the shape-selective properties of the coating, achieving high selectivity for isomerization while minimizing cracking reactions
3Temperature
If extraction using solvents such as propane or MEK is performed to reduce pour point, then cold-weather properties are improved, but the process becomes expensive and time-consuming
Solution Approach 1:
The invention replaces the mechanical extraction process (which requires solvent contact, separation, and recovery operations) with a catalytic chemical process. The beta zeolite catalyst directly transforms long paraffinic chains into isomerized products with lower pour point in a single reaction step, eliminating the time-consuming extraction operations while achieving the same cold-weather property improvement
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 process improves the isomerization selectivity and maintains activity of the catalyst, allowing for the production of middle distillates with better cold resistance by preferentially isomerizing long paraffins, thereby reducing pour points and improving the suitability of these fuels for use in diesel and kerosene pools.
Implementation Method 1
at least one heat treatment step in which the solid prepared in step ii) is brought into contact with at least one gaseous mixture containing oxygen, water, chlorine and/or at least one chlorinated compound
Implementation Method 2
heat treatment with a gas mixture containing oxygen, water, and chlorine
Implementation Method 3
A bifunctional catalyst comprising IZM-2 zeolite and a noble metal from group VIII, such as platinum, is prepared
Data Source
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AI summary
The present invention relates to a method for preparing a bifunctional catalyst using an IZM-2 zeolite, a hydrogenating function and a matrix. The preparation method according to the invention uses a specific heat treatment of the catalyst which improves its selectivity for the isomerisation of paraffinic feedstocks in middle distillates.