Rhenium-Based Catalyst for Hydrogen Production Selectivity
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Solution Overview
Problem
Catalysts for catalytic partial oxidation processes tend to favor production of gases with a H2/CO ratio less than 2:1 due to side-reactions, requiring high temperatures and leading to catalyst deactivation, and existing support materials face challenges in stability and durability at elevated temperatures.
Innovation Solution
A high-efficiency catalyst comprising rhenium and a second metal (platinum, iridium, ruthenium, or palladium) on an alumina support, with a specific atomic ratio and preparation method to maintain the catalyst in a reducing environment, avoiding oxidizing conditions above 360°C, which enhances stability and selectivity for hydrogen and carbon monoxide production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional catalysts are used for catalytic partial oxidation, then hydrogen and carbon monoxide production is achieved, but the H2/CO ratio is less than 2:1 due to side-reactions
Solution Approach 1:
The patent changes the catalyst composition parameters by using rhenium combined with platinum group metals (Pd, Pt, Rh, Ru, or Ir) in specific weight ratios (Re:PGM from 1:9 to 9:1), which fundamentally alters the reaction pathway and product distribution to achieve the desired H2/CO ratio of 2:1 while minimizing side-reactions
2Reliability
If high temperature is used to achieve high selectivity with rhodium catalyst, then hydrogen and carbon monoxide production is improved, but catalyst deactivation occurs
Solution Approach 1:
The patent replaces expensive rhodium with a more stable rhenium-based catalyst system that operates effectively at lower temperatures (600-900°C), achieving both high selectivity and long-term stability without the deactivation problems associated with traditional rhodium catalysts at high temperatures
Solution Approach 2:
The patent creates a composite catalyst material combining rhenium with platinum group metals (Pd, Pt, Rh, Ru, or Ir) supported on alumina, where the synergistic interaction between Re and PGM enhances both activity and stability, allowing operation at moderate temperatures that prevent catalyst deactivation
3Ease of manufacture
If monolith support is used for catalyst, then catalyst engineering is achieved, but feed bypass and instability occur due to expansion differences
Solution Approach 1:
The patent uses porous alumina support with controlled pore structure and surface properties that provide high catalyst dispersion and activity while maintaining thermal stability, eliminating the expansion mismatch problems associated with monolith supports at elevated temperatures
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 maintains high methane conversion and selectivity for hydrogen and carbon monoxide at high gas hourly space velocities for a longer period, achieving a desired H2/CO ratio of 2:1 with improved stability and durability compared to traditional rhodium catalysts.
Implementation Method 1
catalytic partial oxidation (COPx) processes. In catalytic partial oxidation processes the gaseous hydrocarbon feedstock is mixed with air, oxygen-enriched air, or oxygen, in the presence of a catalyst
Implementation Method 2
the catalyst must be activated in a reducing environment at temperatures higher than 350° C. before using in a CPOx process
Data Source
AI summary
A high efficiency catalyst for use in a catalytic partial oxidation process for the production of hydrogen or syngas gas from hydrocarbons is disclosed. The catalyst comprises rhenium in combination with a second metal selected from the group of rhenium to second metal of 25:1 to 1:1. the process comprises reacting a feed containing hydrocarbons with an oxygen source at a C/O ratio of about 0.9 to 1.1 in the presence of the catalyst, and wherein the gas hourly space velocity of the feed over the catalyst ranges from about 1,000 hr−1 to about 2,000,000 hr −1. In the process, the catalyst is maintained as a temperature of from about 500° C. to about 1,500° C. as the feed makes contact with the catalyst.