Hydrogen Generator Catalyst Submergence Control
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Solution Overview
Problem
Existing hydrogen generation systems, such as those using sodium borohydride, face issues with handling water, catalyst reactivity, and by-product treatment, making them unsuitable for heavy-duty applications, and also suffer from low hydrogen production density and high costs due to the use of noble metals.
Innovation Solution
A hydrogen generator with a container holding a soluble chemical fuel solution and a catalyst holder, where the depth of catalyst submergence is controlled by pressure differences to regulate hydrogen generation based on demand, using a cobalt oxide-based catalyst and a control cylinder with a piston mechanism to optimize hydrogen production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If noble metal catalysts (Pt, Pd) are used to accelerate the hydrolysis reaction of sodium borohydride, then the hydrogen generation rate is improved, but the system cost increases significantly
Solution Approach 1:
The patent replaces expensive noble metal catalysts with a disposable aluminum foil-based catalyst support that provides sufficient catalytic activity for hydrogen generation. The aluminum foil is consumed during the reaction process, but eliminates the need for costly Pt or Pd catalysts while maintaining acceptable hydrogen generation rates for portable applications.
Solution Approach 2:
The patent uses a composite structure combining aluminum foil with sodium borohydride solution, where the aluminum foil serves as both the catalyst support and a reactant. This composite approach enhances the catalytic efficiency compared to using aluminum foil alone, while still avoiding noble metals.
2Productivity
If the catalyst is fully submerged in the chemical fuel solution, then the hydrogen production density is maximized, but the catalyst reacts too quickly and deactivates prematurely
Solution Approach 1:
The patent employs a dynamic control mechanism where the catalyst holder can be moved vertically to adjust the submergence depth of the aluminum foil catalyst in the sodium borohydride solution. This allows the system to optimize the balance between hydrogen generation rate and catalyst longevity by controlling the contact area between catalyst and fuel solution based on operational needs.
Solution Approach 2:
The patent changes the operational parameter of catalyst submergence depth to control the reaction intensity. By adjusting how much of the aluminum foil catalyst is submerged in the sodium borohydride solution, the system can modulate the hydrogen generation rate to prevent premature catalyst deactivation while maintaining sufficient productivity.
3Productivity
If a fixed bed reactor design is used with continuous catalyst contact, then the hydrogen generation is continuous, but the catalyst deactivates quickly and requires frequent replacement
Solution Approach 1:
The patent transforms the static fixed bed reactor design into a dynamic system where the catalyst holder can be moved up and down. This allows the aluminum foil catalyst to be periodically withdrawn from the sodium borohydride solution to prevent complete deactivation, extending catalyst life while maintaining continuous hydrogen generation capability through controlled intermittent contact.
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 system provides a cost-effective, demand-regulated hydrogen generation with improved energy density, suitable for portable applications, by automatically adjusting the catalyst's submergence and thus the hydrogen production rate to match the consumption needs of the device, reducing the need for noble metals and enhancing system efficiency.
Implementation Method 1
the hydrolysis of sodium borohydride has been successfully demonstrated
Implementation Method 2
a robust self-support cobalt oxide-based catalyst is used as an alternative catalyst to accelerate the hydrolysis reaction of sodium borohydride
Implementation Method 3
the depth of catalyst submergence is controlled by pressure differences to regulate hydrogen generation based on demand
Data Source
AI summary
A hydrogen generator includes a container having a gas outlet that is configured to contain a soluble chemical fuel that reacts with a catalyst to generate hydrogen. A control cylinder is attached to the container and comprises a piston configured to travel axially within the control cylinder, a pole attached to the piston and extending into the container, a catalyst holder provided within the container and connected to the pole, resilient means biasing the catalyst holder towards a bottom of the container, and a gas inlet port. A gas flow line is in fluid communication with the gas outlet and has a first end in fluid communication with the gas inlet port, a second end configured to feed hydrogen to a hydrogen-consuming device, and a two-way valve provided to allow fluid communication between the first and second ends of the gas flow line to be selectably established or cut off.