Abstract:

Sorption enhanced water gas shift reaction (SEWGS) is one of the critical reactions for high-purity hydrogen preparation and carbon dioxide emission reduction. The composite catalyst is utilized to couple catalytic water gas shift (hydrogen production) with in-situ CO₂ removal (decarbonization) during SEWGS, which could break the thermodynamic limitations by moving the chemical equilibrium towards the hydrogen production to achieve enhanced hydrogen production. SEWGS has the characteristic of one-step production of high-purity hydrogen. However, problems with the composite catalyst, such as sintering and hindered CO₂ diffusion during continuous SEWGS hydrogen production, lead to a decrease in cycle stability, thereby affecting the hydrogen production efficiency. This work elaborates on the current research status of high-temperature Ni/CaO-based composite catalysts for sorption enhanced hydrogen production. The existing problems of Fe/CaO-based composite catalysts in SEWGS for hydrogen production are briefly described. The current status and core problems of medium temperature Cu/MgO-based and Cu/layer double hydroxides are discussed. From the perspectives of the catalytic components and the sorbent components of composite catalysts, the reasons for the reduced stability are analyzed, and the most effective modification methods currently available are briefly described. Furthermore, modification strategies are proposed from the design of the composite catalyst, operational conditions, and bed loading methods of reactor, to improve the cycle stability of composite catalyst, focusing on enhancing CO₂ diffusion and lowering sintering resistance. It highlights that the design and development of composite catalysts that are simple in composition, easy to prepare, as well as high activity and stability, for the coupled production of hydrogen and decarbonization, are the future research direction in SEWGS for hydrogen production.

Key words: hydrogen production, composite catalyst, water gas shift reaction, sorption enhanced, CO₂ diffusion, sintering, stability

摘要：

吸附强化水气变换反应（SEWGS）是实现高纯氢制备及二氧化碳（CO₂）减排的关键反应之一。SEWGS借助复合催化剂将水气变换反应（制氢）和原位移除CO₂反应（脱碳）耦合，打破热力学限制使反应平衡向制氢侧移动。SEWGS具有一步制取高纯氢气的特点，但复合催化剂在连续操作过程中由于烧结和CO₂扩散受阻存在循环稳定性下降的问题，进而影响制氢效率。本文阐述了高温Ni/CaO基复合催化剂吸附强化制氢的研究现状，简述了Fe/CaO基复合催化剂SEWGS制氢面临的主要问题，回顾了中温Cu/MgO基和Cu/类水滑石基复合催化剂的SEWGS制氢现状及现阶段的核心问题。从复合催化剂的催化组分和吸附组分角度，分析了SEWGS制氢过程中复合催化剂循环稳定性降低的原因，简述了现阶段最有效的改性手段。进一步从增强CO₂扩散和改善烧结角度入手，围绕复合催化剂设计、操作条件和床层装填方式等方面探讨提高复合催化剂循环稳定性的策略。指出设计开发组成简单、易制备、兼具高活性和高稳定性的复合催化剂实现制氢和脱碳耦合是今后SEWGS制氢的研究方向。

关键词: 制氢, 复合催化剂, 水气变换反应, 吸附强化, CO₂扩散, 烧结, 稳定性