Copper-Chlorine Thermochemical Cycle for Hydrogen Production
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Solution Overview
Problem
Current hydrogen production methods face challenges in reducing greenhouse gas emissions and reliance on hydrocarbon fuels, with existing thermochemical cycles requiring high temperatures and complex handling of hazardous materials.
Innovation Solution
A six-step thermochemical copper-chlorine (Cu—Cl) cycle is developed, involving thermal and electrochemical reactions to split water into hydrogen and oxygen, using a closed loop system with copper and chlorine compounds, which operates at lower temperatures and recycles all reactants without emitting greenhouse gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional hydrogen production methods (steam reforming, partial oxidation, coal gasification) are used, then hydrogen can be produced, but greenhouse gas emissions and reliance on hydrocarbon fuels increase
Solution Approach 1:
The invention changes the fundamental parameters of hydrogen production by transitioning from hydrocarbon-based processes to water splitting through thermochemical cycles. The Cu-Cl cycle operates at moderate temperatures (550°C) compared to conventional high-temperature processes, and uses water as feedstock instead of hydrocarbons, fundamentally altering the chemical reactions and energy pathways to eliminate CO2 emissions while maintaining hydrogen production efficiency
Solution Approach 2:
The invention utilizes phase transitions in the Cu-Cl thermochemical cycle, including melting of CuCl at reaction temperatures, condensation of HCl gas, and phase changes in molten salt heat transfer media. These phase transitions enable efficient heat transfer and reaction progression at lower temperatures, achieving high hydrogen production rates without the high temperatures required by conventional methods
2Productivity
If high temperature thermochemical cycles are used for hydrogen production, then water splitting efficiency improves, but temperature requirements and energy input increase
Solution Approach 1:
The invention introduces copper-chlorine compounds as intermediary substances that facilitate water splitting at lower temperatures. The Cu-Cl cycle uses intermediate chemical reactions (Cu + HCl → CuCl + H2, followed by CuCl oxidation and decomposition) to break down water indirectly, avoiding the need for direct high-temperature water decomposition. This intermediary approach enables efficient hydrogen production at 550°C compared to direct thermal decomposition requiring temperatures above 2000°C
Solution Approach 2:
The invention replaces direct thermal-mechanical water splitting with a chemical reaction-based thermochemical cycle. Instead of using mechanical energy or direct high-temperature thermal decomposition, the system uses a series of coupled chemical reactions involving copper and chlorine compounds that proceed at lower temperatures, substituting a chemical mechanism for a purely thermal-mechanical process
3Productivity
If complex thermochemical cycles are used, then hydrogen production becomes feasible, but handling of hazardous materials and process complexity increase
Solution Approach 1:
The invention segments the water splitting process into six distinct but integrated steps: (1) Cu oxidation, (2) CuCl formation, (3) HCl generation, (4) H2 production, (5) CuCl2 formation, and (6) O2 evolution. Each step is carried out in a separate reactor or process unit, allowing independent optimization and control of each reaction while maintaining overall system integration. This segmentation reduces the complexity of managing all reactions simultaneously in a single complex system
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 Cu—Cl cycle efficiently produces hydrogen and oxygen using clean energy sources like nuclear and solar, reducing environmental impact and dependence on hydrocarbon fuels, while minimizing hazardous material handling and operating costs.
Implementation Method 1
contacting of copper with dry hydrogen chloride (HCl) to form cuprous chloride (CuCl) and hydrogen gas
Implementation Method 2
electrolysis of CuCl of step a) to produce copper and cupric chloride (CuCl2)
Implementation Method 3
hydrolysis of CuCl2 of step b) to produce cupric oxide (CuO) and hydrogen chloride (HCl)
Implementation Method 4
reacting CuO with chlorine to produce CuCl and oxygen gas
Implementation Method 5
CuCl2 is partially decomposed to produce CuCl and Cl2(g)
Data Source
AI summary
The present invention discloses a method for thermochemical production of hydrogen and oxygen from water by a low temperature, multi-step, closed, cyclic copper-chlorine (Cu—Cl) process involving the reactions of copper and chlorine compounds. A method for production of hydrogen via Cu—Cl thermochemical cycle consists of four thermal reactions and one electrochemical reaction and one unit operation. The cycle involves six steps: (1) hydrogen production step; (2) copper production step; (3) drying step; (4) hydrogen chloride production step; (5) decomposition step; (6) oxygen production step. The net reaction of the sequential process is the decomposition of water into hydrogen and oxygen. The methods for production of copper oxide which comprises contacting copper chloride particles with superheated steam and production of oxygen comprises reaction of copper oxide with dry chlorine as a part of hydrogen production by thermochemical Copper-Chlorine (Cu—Cl) cycle. The reactions are performed in a flow through type quartz reactor as fixed bed type at high temperature and atmospheric pressure.