Bio-based LPG Production via Fermentation and Catalytic Conversion
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Solution Overview
Problem
Current bio-based methods for producing liquefied petroleum gas (LPG) are limited by the availability of waste oils and result in only about 5% of starting carbon being converted into LPG, necessitating the development of more efficient and sustainable production methods.
Innovation Solution
The method involves microbial fermentation of gaseous substrates to produce alcohols, which are then converted into propane and butane using dehydration and hydrogenation catalysts, such as acidic alumina and Ni-alumina, in a process that includes dehydration of C3 and C4 alcohols, dimerization of ethylene, and carbonylation of ethanol, to produce LPG from bio-based or sustainable feedstocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the HEFA process is used to convert tri-glycerides to diesel range materials, then propane is produced as a byproduct, but the amount of LPG produced is limited to only about 5% of starting carbon due to limited availability of waste oils
Solution Approach 1:
The patent changes the feedstock parameter from waste oils to gaseous substrates (CO, CO2, H2) and alters the chemical conversion pathway from hydrogenolysis of tri-glycerides to fermentation followed by dehydration and hydrogenation. This parameter change enables production of LPG from abundant gaseous carbon sources rather than limited waste oils, directly resolving the contradiction between LPG quantity and feedstock availability
Solution Approach 2:
The patent extracts the carbon production pathway from the HEFA process by separating the propane byproduct generation from the main diesel production. Instead of relying on propane as a minor byproduct of triglyceride conversion, the invention creates a dedicated fermentation-based pathway that produces C3 and C4 alcohols which are then converted to LPG, effectively extracting and amplifying the LPG production capability independent of waste oil constraints
2Productivity
If multiple catalytic steps (dehydration and hydrogenation) are introduced to convert alcohols to LPG, then the yield and efficiency of LPG production increases, but the device complexity and process steps increase
Solution Approach 1:
The patent segments the complex conversion process into distinct functional stages: fermentation of gaseous substrates to produce alcohols, dehydration of alcohols to alkenes using acidic catalysts, and hydrogenation of alkenes to alkanes using metal catalysts. This segmentation allows each step to be optimized independently with specific catalysts and conditions, improving overall productivity while managing complexity through modular process design
Solution Approach 2:
The patent employs universal catalyst systems that can handle multiple alcohol substrates (C2-C4 alcohols from various fermentation pathways) through the same dehydration and hydrogenation sequence. The acidic dehydration catalysts and metal hydrogenation catalysts serve multiple functions across different carbon chain lengths, enabling a single process configuration to produce various LPG components (propane, butane, isobutane) from diverse fermentation products, thereby increasing productivity without proportionally increasing device complexity
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 approach enhances the production of LPG while reducing greenhouse gas emissions and increases the yield beyond traditional methods, utilizing renewable resources effectively.
Implementation Method 1
C1-fixing microorganisms have been demonstrated to convert gases comprising CO2, CO, CH4, and/or H2 into products such as ethanol and 2,3-butanediol
Implementation Method 2
contacting the feed stream comprising a C3 alcohol, such as isopropanol and/or 1-propanol, and/or a C4 alcohol, such as butanol or an isomer of butanol, with one or more catalysts to produce a product stream comprising propane and/or butane
Implementation Method 3
the one or more catalysts comprise a dehydration catalyst and/or a hydrogenation catalyst
Data Source
AI summary
The disclosure provides methods for the production of liquefied petroleum gas from sustainable feedstocks, including methods comprising conversion of alcohols produced by gas fermentation for the production of propane and/or butane.