Extruded C8 Isomerization Catalyst with Alkali Control
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Solution Overview
Problem
Current catalysts for C8 aromatic isomerization processes face challenges in minimizing C8 ring loss while maximizing para-xylene yield, often requiring a compromise between high conversion and high utility costs due to cyclic C8 loss and unconverted aromatic recycle rates.
Innovation Solution
An extruded C8 alkylaromatic isomerization catalyst comprising 2-20% MTW zeolite, 80-98% alumina binder, 0.01-2% noble group metal, and 100 ppm-less than 1000 ppm alkali metal, which minimizes C8 ring loss during the isomerization of non-equilibrium C8 aromatic feeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the isomerization process is run close to equilibrium to maximize para-xylene yield, then the para-xylene yield is improved, but the C8 cyclic loss increases due to side reactions
Solution Approach 1:
The patent applies parameter changes by precisely controlling the alkali metal content within 100-1000 ppm ranges and using specific silica-to-alumina ratios (5:1 to 20:1) in the zeolite structure. These parameter optimizations modify the catalyst's acid site distribution and strength, enabling the process to achieve near-equilibrium conversion while suppressing excessive cyclic losses through tailored catalytic activity
Solution Approach 2:
The patent employs composite materials by combining zeolite with specific binders and incorporating noble metals (0.01-2.00% by weight) along with controlled alkali metal content. This composite structure creates a synergistic catalyst system where the zeolite provides shape selectivity, the binder offers structural support, and the metal components enhance catalytic activity while minimizing side reactions that cause cyclic loss
2Productivity
If high conversion is achieved to maximize para-xylene yield, then the para-xylene yield is improved, but the utility costs increase due to large recycle rates of unconverted C8 aromatic
Solution Approach 1:
The patent optimizes operational parameters including temperature (250-500°C), pressure (1-20 atm), and liquid hourly space velocity (0.1-10 hr⁻¹) to achieve high conversion in a single pass. The controlled alkali metal content (100-1000 ppm) and silica-to-alumina ratio (5:1 to 20:1) fine-tune the catalyst's activity, enabling the process to reach near-equilibrium conversion without requiring excessive recycle rates, thereby reducing energy consumption for compression and heating
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 a C8 ring loss of no more than 2.5%, enhancing para-xylene yield while reducing operational costs by optimizing catalyst composition and process conditions.
Implementation Method 1
about 2-about 20%, by weight, of an MTW zeolite
Implementation Method 2
about 80-about 98%, by weight, of a binder including an alumina
Data Source
AI summary
One exemplary embodiment can be an extruded C8 alkylaromatic isomerization catalyst. The extruded catalyst can include:about 2-about 20%, by weight, of an MTW zeolite;about 80-about 98%, by weight, of a binder including an alumina;about 0.01-about 2.00%, by weight, of a noble group metal calculated on an elemental basis; andabout 100 ppm-less than about 1000 ppm, by weight, of at least one alkali metal calculated on an elemental basis.Generally, the weight percents of the MTW zeolite, the binder, the noble group metal, and the at least one alkali metal are based on a weight of the extruded catalyst.