UZM-39 Zeolite Catalyst Methane Conversion Coking
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Solution Overview
Problem
Current methods for converting low carbon number aliphatic hydrocarbons, such as methane, to aromatic compounds like benzene suffer from low yields and high production of tar and insoluble carbon residues, with catalysts like Mo/HZSM-5 experiencing deactivation issues due to coking and repetitive regeneration.
Innovation Solution
A novel catalytic composite comprising coherently grown composite of TUN and IMF zeotypes designated UZM-39, which is thermally stable and less prone to deactivation, is used to convert low carbon number aliphatic hydrocarbons to aromatic hydrocarbons, optionally with promoters like iron, cobalt, tungsten, or molybdenum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catalysts like Mo/HZSM-5 are used for converting methane to aromatic compounds, then the conversion process can proceed, but the catalyst experiences deactivation due to coking and requires repetitive regeneration, reducing reliability
Solution Approach 1:
The patent employs a composite catalyst system comprising UZM-39 zeolite combined with metal promoters (Fe, Co, Mo, or W). This composite structure integrates the shape-selective catalysis of UZM-39 with the promotional effects of metals to enhance aromatic compound selectivity and suppress coking, thereby improving catalyst stability and extending operational lifetime without requiring frequent regeneration.
Solution Approach 2:
The patent modifies catalyst composition parameters by incorporating specific metal promoters (Fe, Co, Mo, or W) at controlled levels into the UZM-39 zeolite structure. These compositional changes alter the catalytic properties to reduce coke formation and improve resistance to deactivation, enabling sustained operation under methane conversion conditions.
2Productivity
If conventional catalysts are used for methane conversion, then the process can operate, but yields of aromatic compounds are low and significant tar and insoluble carbon residues are produced
Solution Approach 1:
The patent utilizes the unique local pore structure and acid site distribution of UZM-39 zeolite to create favorable microenvironments for methane activation and aromatic formation. The specific pore geometry and promoter locations provide localized catalytic functions that enhance aromatic yield while suppressing side reactions leading to tar and carbon residue formation.
Solution Approach 2:
The patent converts the potential harmful effect of coke formation into a beneficial selectivity mechanism. The controlled presence of metal promoters on UZM-39 creates active sites that favor aromatic compound formation while the zeolite structure naturally limits excessive carbon deposition, transforming what would be a deactivation mechanism into a selectivity-enhancing feature that reduces tar and residue production.
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
UZM-39 catalysts achieve higher conversion rates and selectivity to aromatic compounds with reduced deactivation, allowing for more efficient and stable operation in hydrocarbon conversion processes.
Implementation Method 1
UZM-39 catalysts achieve higher conversion rates and selectivity to aromatic compounds
Data Source
AI summary
A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and shown to be effective catalysts in processes for converting at least one aliphatic hydrocarbon having from 1 to about 4 carbon atoms in a feedstream to provide at least one aromatic hydrocarbon. These zeolites are represented by the empirical formula.NanMmk+TtAl1-xExSiyOz where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, T is the organic structure directing agent or agents and E is a framework element such as gallium. The process involves contacting a low carbon number aliphatic hydrocarbon with the coherently grown composite of TUN and IMF zeotypes to produce at least an aromatic.