Composite Oxide Ruthenium Catalyst for Low-Pressure Ammonia Synthesis
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Solution Overview
Problem
Existing ammonia synthesis catalysts, particularly those using ruthenium supported by rare earth oxides, face challenges in achieving high activity and efficiency under milder conditions, such as lower temperatures and pressures, and require easier handling for catalyst replacement.
Innovation Solution
A composite oxide is developed as a carrier for ruthenium, comprising specific compositions of lanthanoid, Group-2, and Group-1 elements, with controlled partial negative charge of oxygen, which supports ruthenium to enhance catalyst activity and facilitate easier handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ruthenium catalyst is supported by rare earth oxide carrier to reduce usage of ruthenium and reaction temperature, then reaction temperature is reduced, but ammonia yield at lower pressure is insufficient
Solution Approach 1:
The patent uses a composite oxide carrier composed of multiple rare earth elements (lanthanum, cerium, and praseodymium oxides) instead of a single rare earth oxide. This composite structure synergistically combines the properties of individual oxides to achieve both low-temperature activity and high ammonia yield, resolving the contradiction between temperature reduction and productivity maintenance.
2Productivity
If iron-based catalyst is used in Haber-Bosch process to synthesize ammonia, then ammonia synthesis is achieved, but very high temperature and high pressure are required
Solution Approach 1:
The patent fundamentally changes the catalytic parameters by replacing iron-based catalysts with ruthenium-based catalysts supported on optimized rare earth oxide carriers. This parameter change enables ammonia synthesis at dramatically lower temperatures (reducing energy consumption) while maintaining or improving synthesis efficiency, directly addressing the high temperature requirement of conventional Haber-Bosch processes.
3Stress or pressure
If ruthenium catalyst is used to manufacture ammonia at lower pressure, then pressure is reduced, but ammonia yield is insufficient
Solution Approach 1:
The composite oxide carrier containing lanthanum, cerium, and praseodymium oxides creates a synergistic effect that enhances catalyst activity at low pressure. The multiple rare earth elements work together to improve the electronic and structural properties of the carrier, enabling high ammonia yield even when operating pressure is reduced, thus resolving the contradiction between pressure reduction and productivity.
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 composite oxide-based catalyst achieves higher ammonia yield under milder conditions compared to the Haber-Bosch process, with improved activity and handling characteristics.
Implementation Method 1
a ruthenium catalyst that is used in the manufacture of ammonia is usually supported by a carrier
Implementation Method 2
obtain a catalyst that can synthesize ammonia under a milder condition (lower temperature and lower pressure) than that for an iron-based catalyst
Data Source
AI summary
A metal-supported material including a transition metal excluding Group 4 elements supported on a binary composite oxide. The composite oxide includes a metal element expressed by AnXy, where A represents a lanthanoid that is in a partially or entirely trivalent state, X represents an element that is a Group-2 element in a periodic table selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid, and that is different from A, n satisfies 0<n<1, y satisfies 0<y<1, m satisfies 0≤m<1, and n+y=1. The composite oxide includes a solid solution that is a tetragonal crystal or a cubic crystal, and a ratio of a value (Dads) of a dispersion degree of the transition metal obtained by an H2 pulse chemical adsorption method to a value (DTEM) of the dispersion degree predicted from an average particle diameter of particles of the transition metal obtained from a TEM image satisfies 0<Dads/DTEM<1.