Dehydrocyclization Catalyst for High Conversion Low Methane
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Solution Overview
Problem
Current processes for producing aromatic hydrocarbons from C2+ non-aromatic hydrocarbons face challenges in achieving high feed conversion with low methane selectivity, often resulting in catalyst deactivation and complex separation processes.
Innovation Solution
A catalytic process utilizing a dehydrocyclization catalyst with a molecular sieve component and a dehydrogenation component, operating at temperatures between 400°C to 800°C and pressures from 0 to 300 psig, with an average residence time of ≤90 seconds, which increases feed conversion to ≥65 wt.% while minimizing methane selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature and low pressure conditions are used to increase aromatic hydrocarbon yield, then the yield of aromatic hydrocarbon is improved, but the rate of catalyst deactivation increases due to increased catalyst coking
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst composition parameters - specifically incorporating molecular sieve components with controlled silica-to-alumina ratios (5:1 to 20:1) and combining them with dehydrogenation metals (Ga, Zn, Cu, Re, Mo, W, La, Fe, Ag, Pt, or Pd) at controlled loadings (0.005-10 wt%). This compositional parameter optimization allows the catalyst to maintain high aromatic yield while resisting deactivation by balancing dehydrocyclization activity with reduced coking tendency.
Solution Approach 2:
The patent employs composite materials by creating a bifunctional catalyst system that combines molecular sieve components (providing shape selectivity and acid catalysis) with dehydrogenation metal components (providing dehydrogenation activity). This composite structure, where the molecular sieve framework supports dispersed metal sites, enables simultaneous dehydrogenation and cyclization while the molecular sieve's pore structure limits coke precursor formation, thus resolving the contradiction between productivity and reliability.
2Reliability
If C2+ hydrocarbon is removed from the feed to increase methane content, then the amount of catalyst coking is lessened, but the feed conversion efficiency decreases
Solution Approach 1:
The patent changes the catalyst's chemical parameters by optimizing the molecular sieve's silica-to-alumina ratio to a specific range (5:1 to 20:1) and controlling metal loading levels. These parameter changes make the catalyst sufficiently stable to handle C2+ hydrocarbons without excessive coking, eliminating the need to remove C2+ components from the feed and thereby maintaining high feed conversion efficiency.
Solution Approach 2:
The patent effectively makes the catalyst more durable (less disposable) by designing it with enhanced stability features - the molecular sieve framework provides structural stability while the optimized metal dispersion provides sustained dehydrogenation activity. This extended catalyst life allows continuous processing of C2+ hydrocarbons without frequent regeneration or replacement, maintaining both reliability and productivity.
3Productivity
If dehydrocyclization is carried out for extended periods to achieve high conversion, then feed conversion is improved, but catalyst deactivation occurs due to coke accumulation
Solution Approach 1:
The patent enables continuous operation by designing a catalyst that maintains activity over extended periods. The molecular sieve component continuously provides shape-selective catalysis while the dehydrogenation metals continuously facilitate dehydrogenation, and the optimized structure continuously resists coking. This continuous stable operation allows sustained high conversion without periodic shutdowns for regeneration.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating structural features in the catalyst design that preemptively resist coke formation - the molecular sieve pore structure and optimized metal dispersion create a catalyst architecture that prevents coke precursor accumulation before it can deactivate the catalyst. This proactive design allows extended operation without deactivation.
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 achieves high conversion of C2+ non-aromatic hydrocarbons to aromatic hydrocarbons with reduced methane selectivity, effectively addressing catalyst deactivation and simplifying separation processes.
Implementation Method 1
The invention relates to the production of aromatic hydrocarbon by the conversion of a feed comprising C2+ non-aromatic hydrocarbon. The conversion is carried out in the presence of a dehydrocyclization catalyst comprising dehydrogenation and molecular sieve components.
Implementation Method 2
The dehydrocyclization catalyst comprises dehydrogenation and molecular sieve components
Implementation Method 3
The dehydrocyclization catalyst comprises dehydrogenation and molecular sieve components
Data Source
AI summary
The invention relates to the production of aromatic hydrocarbon by the conversion of a feed comprising C2+ non-aromatic hydrocarbon, e.g., natural gas. The invention is particularly useful in converting natural gas to liquid-phase aromatic hydrocarbon, which can be more easily transported away from remote natural gas production facilities. The conversion is carried out in the presence of a dehydrocyclization catalyst comprising dehydrogenation and molecular sieve components. The dehydrocyclization catalyst has an average residence time of 90 seconds or less.