Ethanol Reforming Catalyst System for Hydrogen Production
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Solution Overview
Problem
Steam reforming of ethanol to hydrogen is hindered by the formation of carbon polymer due to ethylene intermediate products, which causes catalyst deactivation and requires suppression of ethylene content.
Innovation Solution
A process involving a dual catalytic system where ethanol is dehydrated to ethylene and then hydrogenated to ethane, followed by steam reforming of ethane to produce a hydrogen-rich product, with hydrogen recycling to maintain high partial pressures and suppress ethylene formation, using catalysts like alumina and noble metals supported on acidic oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ethanol is steam reformed to produce hydrogen, then hydrogen production is achieved, but carbon polymer formation occurs causing catalyst deactivation
Solution Approach 1:
The patent applies preliminary action by introducing a dehydration/hydrogenation reactor before the steam reforming step. This preliminary conversion transforms ethanol into ethane through intermediate ethylene, preventing ethylene from reaching the steam reforming catalyst where it would form carbon polymer. The preliminary action eliminates the harmful ethylene before it can cause catalyst deactivation.
Solution Approach 2:
The patent uses an intermediary substance (ethane) to replace the harmful intermediate (ethylene). By converting ethanol to ethane through controlled dehydration and hydrogenation in the first reactor, the process eliminates ethylene formation. Ethane then serves as the feedstock for steam reforming, producing hydrogen without generating carbon polymer on the catalyst.
2Object-affected harmful factors
If ethylene is suppressed by adding hydrogen, then carbon polymer formation is reduced, but process complexity increases due to hydrogen recycling
Solution Approach 1:
The patent merges the hydrogen production from steam reforming with the hydrogen consumption in the dehydration/hydrogenation reactor. The hydrogen-rich stream from the steam reforming unit is recycled back to the first reactor, creating an integrated system where the output of one process feeds the input of another. This eliminates the need for external hydrogen sources and reduces overall process complexity.
Solution Approach 2:
The process achieves self-service by using the hydrogen produced during steam reforming of ethane to suppress ethylene formation in the dehydration/hydrogenation reactor. The system is self-sufficient, generating its own hydrogen requirement internally through the steam reforming step, eliminating dependence on external hydrogen supplies.
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
This process effectively reduces carbon polymer formation, maintains catalyst activity, and achieves high selectivity in hydrogen production suitable for fuel cells by controlling ethylene concentrations and recycling hydrogen.
Implementation Method 1
transferring a stream of ethanol and steam and a hydrogen-comprising stream, the molar ratio of ethanol to hydrogen being 0.2-1, to a dehydration/hydrogenation reactor for dehydrating ethanol to ethylene
Implementation Method 2
for hydrogenating ethylene to produce an ethane-comprising stream
Implementation Method 3
steam reforming the stream comprising methane to produce a mixture comprising hydrogen and carbon monoxide
Implementation Method 4
converting the mixture comprising hydrogen and carbon monoxide from the steam reforming step under water gas shift conditions to produce a hydrogen-rich product stream
Data Source
AI summary
Process for selectively reforming ethanol to a hydrogen-rich product in the presence of at least one catalyst comprising a catalytically active material supported on a carrier, the process comprising the following steps in which the at least one catalyst is active:transferring a stream of ethanol and steam and a hydrogen-comprising stream, the molar ratio of ethanol to hydrogen being 0.2-1, to a dehydration/hydrogenation reactor for dehydrating ethanol to ethylene and for hydrogenating ethylene to produce an ethane-containing stream,adiabatically pre-reforming the ethane-comprising stream to a stream comprising methane,steam reforming the stream comprising methane to produce a mixture comprising hydrogen and carbon monoxide,converting the mixture comprising hydrogen and carbon monoxide from the steam reforming step under water gas shift conditions to produce a hydrogen-rich product stream.