Bimetallic Catalysts for Hydrogen Release from Liquid Organic Hydrides
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Solution Overview
Problem
Current hydrogen storage and delivery methods face challenges such as low weight and volumetric capacity, high pressure requirements, long equilibrium periods, and inefficient energy use, particularly in the dehydrogenation of hydrogenated liquid organic compounds.
Innovation Solution
A process using catalysts with the general formula M-M'/support, where M is Ag and M' is selected from Pt, Pd, Rh, dispersed on an activated carbon support, facilitates the dehydrogenation of hydrogenated liquid organic compounds like cyclohexane and decalin, achieving efficient hydrogen release and storage with improved catalytic activity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional hydrogen storage methods (pressurization, liquefaction, physical adsorption) are used, then hydrogen can be stored, but weight basis capacity and volumetric capacity are low
Solution Approach 1:
The invention changes the chemical state of hydrogen from elemental H2 to hydrogenated liquid organic compounds (cycloalkanes, aromatic hydrocarbons). This parameter change enables high-density liquid-phase storage with 6-8 wt% hydrogen content, overcoming the low capacity of conventional gaseous or adsorbed hydrogen storage methods
Solution Approach 2:
The invention uses composite catalyst systems with bimetallic combinations (Pt-Pd, Pt-Rh, Pd-Rh) supported on high-surface-area materials. These composite catalysts achieve synergistic effects that enhance dehydrogenation activity and selectivity, enabling efficient hydrogen release from liquid organic compounds
2Quantity of substance
If dehydrogenation of liquid organic hydrides is used, then high hydrogen content (6-8 wt%) can be achieved, but catalytic activity and selectivity need improvement
Solution Approach 1:
The invention employs bimetallic catalyst combinations (Pt-Pd, Pt-Rh, Pd-Rh) where the two metals work synergistically. The first metal (Pt or Pd) provides primary dehydrogenation activity while the second metal (Rh or Pd) enhances selectivity and prevents side reactions, achieving both high hydrogen content and high dehydrogenation rate
Solution Approach 2:
The invention creates different active sites with different functions on the catalyst surface. The bimetallic structure provides localized regions optimized for C-H bond activation, hydrogen recombination, and product desorption, enhancing overall dehydrogenation efficiency and selectivity
3Device complexity
If monometallic catalysts are used for dehydrogenation, then the process is simpler, but catalytic activity and selectivity are insufficient
Solution Approach 1:
The invention uses bimetallic catalysts where two noble metals are combined on a support. This composite structure provides synergistic effects: one metal activates C-H bonds while the other facilitates hydrogen recombination and release, achieving high dehydrogenation efficiency that monometallic catalysts cannot attain alone
4Ease of manufacture
If existing infrastructure is utilized for hydrogen storage and transport, then cost is reduced, but only liquid-phase storage with specific capacity ranges is feasible
Solution Approach 1:
The invention changes hydrogen from gaseous phase to liquid-phase organic compounds, enabling utilization of existing liquid fuel infrastructure (storage tanks, pipelines, distribution networks). This parameter change achieves cost-effective storage and transport while maintaining high hydrogen density of 6-8 wt%
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 provides high hydrogen storage capacity (2-8 wt%) and efficient delivery, utilizing existing infrastructure for transportation and storage, with conversion efficiencies ranging from 30-98% and 10-62 kg of hydrogen per cubic meter, while being cost-effective and environmentally friendly.
Implementation Method 1
dehydrogenation of hydrogenated liquid organic compounds through dehydrogenation reaction over catalysts with general formula M/support and M-M'/support
Data Source
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AI summary
Hydrogen transportation and delivery to the fueling stations independent of permanent hydrogen transport infrastructure such as pipelines is an important aspect for penetration of hydrogen based energy to mass applications. A method useful for storage and supply of hydrogen at near ambient conditions is storage of hydrogen in hydrogenated liquid organic compounds. The hydrogen from hydrogenated liquid organic compounds can be released through catalytic dehydrogenation reaction. This invention describes the catalysts for dehydrogenation of hydrogenated liquid organic compounds. This consists of two different types of catalysts with general formula M/support and M-M'/support. Where in case of M/support M is at least one metal selected from Pt, Pd, Rh, Ru, Ir, Os and support is metal oxide at least one selected from Y2O3 or V2O5 or combinations thereof. In the second type of catalysts M-M'/support, metal M is at least one metal selected from group 11 of periodic table metals Cu, Ag, Au and metal M' is at least one metal selected from Pt, Pd, Rh, Ru, Ir, Os, Fe, Ni, Re, Mo, W, V, Cr, Co or combinations thereof well dispersed on high surface area supports such as activated carbon, alumina, alumite, zirconia, silica or combinations thereof. The addition of second metal selected from Pt, Pd, Rh, Ru, Ir, Os, Fe, Ni, Re, Mo, W, V, Cr, Co and at least one metal selected from group 11 metals such as Cu, Ag and AU exhibits the synergistic effects of spillover, migration, and recombinations of hydrogen over metallic catalysts having minimum of two metals resulting in shifting of equilibrium to dehydrogenation reaction. The catalyst is placed in a reactor with minimum diffusion area. The reactor is heated, preferably by using renewable energy sources, such as a solar concentrator. The catalysts in this invention provice relatively high activity and selectivity for delivery of hydrogen for fuel cell applications. The method of using hydrogenated liquid organic hydride is useful for efficient storage and transportation of hydrogen.