Permselective Membrane Reactor for Ethanol Reforming
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Solution Overview
Problem
Hydrogen production using permselective membrane reactors faces issues with catalyst deactivation due to coking caused by carbon monoxide disproportionation and inefficient hydrogen separation and recovery, particularly at high permeability membranes.
Innovation Solution
A permselective membrane reactor design with optimized catalyst layer thickness and active component distribution, along with a palladium or palladium alloy membrane, controls the hydrogen recovery rate and catalyst deactivation by managing the ratio of catalyst volume to membrane area and metal mass, reducing carbon monoxide disproportionation and enhancing hydrogen extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a permselective membrane reactor is used to reduce reaction temperature and energy consumption, then energy efficiency is improved, but catalyst deactivation due to coking increases
Solution Approach 1:
The patent changes the chemical environment parameters by introducing CO2 into the reaction system. This parameter change suppresses the disproportionation reaction of CO (2CO → C + CO2) by shifting the equilibrium according to Le Chatelier's principle, thereby preventing carbon deposition on the catalyst while maintaining the low-temperature operation benefits of the membrane reactor
Solution Approach 2:
CO2 acts as an intermediary substance that mediates between the conflicting requirements of low-temperature operation and catalyst protection. By introducing CO2, the system prevents direct carbon deposition on the catalyst surface while maintaining the thermodynamic conditions favorable for hydrogen production, thus protecting catalyst activity without sacrificing energy efficiency
2Productivity
If hydrogen is removed through the permselective membrane to shift reaction equilibrium, then reaction efficiency is improved, but carbon monoxide disproportionation increases causing catalyst deactivation
Solution Approach 1:
CO2 serves as an intermediary that counteracts the harmful effect of CO disproportionation. While hydrogen removal through the membrane promotes reaction equilibrium, the introduced CO2 suppresses carbon formation by providing an alternative reaction pathway (CO + CO2 → 2CO2) that prevents catalyst deactivation
Solution Approach 2:
The patent converts the harmful CO2 that would normally be a product of CO disproportionation into a beneficial substance by intentionally introducing it into the system. This CO2 then acts to suppress further disproportionation reactions, transforming what would be a deactivating pathway into a protective mechanism for the catalyst
3Quantity of substance
If high permeability membrane is used to enhance hydrogen separation, then hydrogen recovery rate is improved, but hydrogen diffusion through catalyst layer becomes inefficient
Solution Approach 1:
The patent optimizes the physical parameters of the system by controlling catalyst layer thickness and adjusting reaction conditions. These parameter changes ensure that hydrogen can efficiently diffuse through the catalyst layer to reach the membrane surface, maximizing the benefit of high membrane permeability while minimizing transport resistance
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 approach effectively reduces catalyst deactivation and improves hydrogen recovery rates between 60% to 99%, maintaining high efficiency and preventing excessive coking, while optimizing catalyst activity and reactor performance.
Implementation Method 1
a permselective membrane selectively permeable to hydrogen on the surface
Implementation Method 2
hydrogen passes selectively through the permselective membrane into the separator tube
Implementation Method 3
a catalyst that promotes the reforming of a hydrocarbon and/or an oxygen-containing hydrocarbon
Implementation Method 4
the reforming catalyst promotes a reforming reaction expressed by the following reaction formula (1)
Implementation Method 5
the reforming catalyst promotes a reforming reaction expressed by the following reaction formula (1) and a shift reaction expressed by the following reaction formula (2)
Implementation Method 6
a disproportionation reaction of carbon monoxide expressed by the following reaction formula (3) occurs more frequently
Data Source
AI summary
A permselective membrane reactor is provided, including a reactor tube having a gas inlet at one end and a gas outlet at the other end thereof. A separator tube is disposed in the reactor tube and has a permselective membrane selectively permeable to hydrogen on a surface thereof and a discharge outlet for passing separated gas through the permselective membrane. The permselective membrane reactor also includes a layer comprising a reforming catalyst that promotes reforming of ethanol, so that β, defined by the following equation, is in a range of 0.05 to 20:β=a/bwherein a denotes the volume of the reforming catalyst layer [cm3], and b denotes the area of the permselective membrane [cm2].