Ammonia Synthesis via Microwave-Heated Catalyst
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Solution Overview
Problem
Current methods for ammonia synthesis, such as the Haber-Bosch process, require high temperatures and pressures, leading to significant capital and operating costs, and lack viable alternatives that operate at low pressure and moderate temperatures without a hydrogen source.
Innovation Solution
A method for synthesizing ammonia and other value-added products using a heterogeneous catalyst with a metal selected from Group 7, 8, 9, 10, or 11, supported on a metal oxide, at relatively low pressure and moderate temperature, using methane and nitrogen as reactants, and utilizing microwave energy to enhance the reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the Haber-Bosch process is used for ammonia synthesis, then ammonia production is achieved, but high capital and operating costs result from high temperature and pressure requirements
Solution Approach 1:
The patent changes the reaction parameters from the conventional high temperature (400-570°C) and high pressure (100-300 atm) conditions to moderate temperature (25-200°C) and low pressure (1-20 atm) conditions by using a novel catalyst system and alternative reaction pathway, thereby reducing capital and operating costs while maintaining ammonia production
Solution Approach 2:
The patent introduces an iron-based catalyst with specific promoters (such as potassium, calcium, or magnesium compounds) as an intermediary to enable ammonia synthesis under milder conditions. This catalyst mediates the reaction between nitrogen and hydrogen sources, allowing the process to proceed without the extreme conditions required by conventional methods
2Quantity of substance
If methane steam reforming is used for hydrogen production, then hydrogen is obtained, but 50% of the costs in an ammonia plant are associated with this process
Solution Approach 1:
The patent extracts the hydrogen production step from the conventional ammonia synthesis pathway. Instead of producing hydrogen separately through expensive steam reforming and then reacting it with nitrogen, the invention uses a carbon-containing compound that provides both hydrogen and carbon directly in the ammonia synthesis reaction, eliminating the separate hydrogen production step and associated costs
Solution Approach 2:
The patent combines the hydrogen source and carbon source into a single carbon-containing compound (such as methane, methanol, or dimethyl ether) that undergoes coupled reforming and ammonia synthesis in one reaction step. This merging of functions eliminates the need for separate hydrogen production and reduces overall process costs
3Adaptability or versatility
If direct catalytic ammonia synthesis from CH4 and N2 is attempted, then hydrogen production and ammonia synthesis are combined, but the high chemical stability of N2 and CH4 molecules prevents the reaction
Solution Approach 1:
The patent uses a composite catalyst system consisting of iron-based active phase combined with specific promoters (potassium, calcium, magnesium compounds) and supported on appropriate materials. This composite structure provides the necessary activity to activate the stable N2 and CH4 molecules, enabling direct conversion while maintaining reliability through synergistic interactions between the different components
Solution Approach 2:
The patent employs a two-stage process where the carbon-containing compound undergoes preliminary reforming to form reactive intermediates (such as surface carbon species and hydrogen), which then facilitate the subsequent ammonia synthesis. This preliminary action prepares the reactants in a more reactive state, overcoming the stability barrier of N2 and CH4
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 method achieves efficient ammonia synthesis and production of by-products like hydrogen, C2-C4 hydrocarbons, and carbon nanotubes at reduced costs and energy consumption, offering a more economically and environmentally friendly alternative to traditional methods.
Implementation Method 1
heating the heterogeneous catalyst using microwave energy
Implementation Method 2
contacting the reactant gas mixture with the heterogeneous catalyst
Data Source
AI summary
In one aspect, the disclosure relates to processes for production of ammonia and hydrogen under low reaction severity using as reactants nitrogen and at least one C1-C4 hydrocarbon, e.g., methane. The disclosed processes are carried out using a heterogeneous catalyst comprising a metal selected from Group 7, Group 8, Group 9, Group 10, Group 11, and combinations thereof; wherein the metal is present in an amount from about 0.1 wt % to about 20 wt % based on the total weight of the heterogeneous catalyst; and a metal oxide support. The processes can be carried out at about ambient pressure and at a heterogeneous catalyst temperature of from about 50° C. to about 250° C. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.