Catalytic and Sulfur-Tolerant Performance of Bimetallic Ni–Ru Catalysts on HI Decomposition in the Sulfur-Iodine Cycle for Hydrogen Production

Lijian Wang,Kang Zhang,Zhihua Wang,Yi Qiu,Huiyun Chen,Jie Wang

doi:10.3390/en14248539

Abstract

The sulfur-iodine (SI) cycle holds great promise as an alternative large-scale process for converting water into hydrogen without CO2 emissions. A major issue regarding the long-term stability and activity of the catalysts is their poor sulfur deactivation resistance in the HI feeding process. In this work, the effect of Ru addition for enhancing the activity and sulfur resistance of SiO2-supported Ni catalysts in the HI decomposition reaction has been investigated. The presence of H2SO4 molecules in the HI results in severe sulfur deactivation of the Ru-free Ni/SiO2 catalysts by blocking the active sites. However, Ni–Ru/SiO2 catalysts show higher catalytic activity without sulfur-poisoning by 25% and exhibit more superior catalytic performance than the Ru-free catalyst. The addition of Ru to the Ni/SiO2 catalyst promotes the stability and activity of the catalysts. The experimental trends in activity and sulfur tolerance are consistent with the theoretical modeling, with the catalytic activities existing in the order Ni/SiO2 < Ni–Ru/SiO2. The effect of Ru on the improvement in sulfur resistance over Ni-based catalysts is attributed to electronic factors, as evidenced by theory modeling analysis and detailed characterizations.

Highlights

Hydrogen is considered as an environment-friendly fuel and sustainable energy vector.Due to its good thermal efficiency and operability, various important efforts have been made to promote hydrogen production via the thermochemical sulfur-iodine (SI) cycle [1,2,3,4,5,6,7,8,9].The SI cycle consists of the following reactions [10]: Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil-SO2 (g) + I2 (s)+2H2 O(l) iations
This study synthesized Ni–Ru bimetallic catalysts and examined the catalytic activity and sulfur tolerance performance of Ni and Ni–Ru catalysts supported on SiO2 in hydrogen iodide (HI) decomposition reactions
Phases are reduced to form metallic Ni during the pre-reduction of the catalyst, which may have been active for HI decomposition

Summary

Introduction

Hydrogen is considered as an environment-friendly fuel and sustainable energy vector.Due to its good thermal efficiency and operability, various important efforts have been made to promote hydrogen production via the thermochemical sulfur-iodine (SI) cycle [1,2,3,4,5,6,7,8,9].The SI cycle consists of the following reactions [10]: Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil-SO2 (g) + I2 (s)+2H2 O(l) iations. Hydrogen is considered as an environment-friendly fuel and sustainable energy vector. Due to its good thermal efficiency and operability, various important efforts have been made to promote hydrogen production via the thermochemical sulfur-iodine (SI) cycle [1,2,3,4,5,6,7,8,9]. The SI cycle consists of the following reactions [10]: Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil-. SO2 (g) + I2 (s)+2H2 O(l) iations.

Methods

Results

Conclusion