New concepts in low‐temperature catalytic hydrogenation and their implications for process intensification

Abstract

The study of dynamic catalytic processes occurring at nanoscale provides necessary information to innovate in process intensification (PI). The present study addresses the catalytic performance of Rh, Cu, and Ru-supported nanoparticles, under mild reaction conditions (< 250 8C, < 500 kPa), for three reactions: (i) the hydrogenation of CO 2 to methane, (ii) the hydrogenation of CO 2 to methanol, and (iii) the hydrogenation of N 2 to ammonia. In all systems, the activity and selectivity are promoted by the presence of large metal nanoparticles, and therefore, a broad distribution of sizes is needed for high activity. The enhanced performance of Rh and Ru nanocatalysts results from catalytic cooperation between small and larger metal nanoparticles. Larger particles provide small ones with the hydrogen needed for an efficient hydrogenation of adsorbed reaction intermediates. Large Cu particles promote methanol formation on Cu/ZnO catalysts, indicating that a similar catalytic cooperation might proceed between large Cu particles and the sites adsorbing reaction intermediates. Some particular crystal planes and defects developed in larger nanoparticles would facilitate the activation and transfer of hydrogen, giving rise to a cooperation mechanism via hydrogen supply. More accurate kinetic models can be developed from a deep understanding of dynamic processes occurring at nanoscale. The new models can be later applied in the design and development of high-performance units and plants. In addition, a multidisciplinary PI approach including the study of nanoscale catalytic processes would certainly lead to important improvements on the existing process technologies.

How do you write and present research well? 14—Favour images over text in graphical abstracts

“…Like Figures and , Figures , , and adopted the geometry for the GA. The rich colours in all three GAs make them very attractive.…”

“…GA caption: Pushing the boundaries in process intensification by integrating the study of nanoscale catalytic phenomena. Title: “New Concepts in Hydrogenation Catalytic Processes Occurring at Nanoscale and their Implications for Process Intensification.”…”

“…Title: "New Concepts in Hydrogenation Catalytic Processes Occurring at Nanoscale and their Implications for Process Intensification." [11] Figure 11. GA caption: Efficient Rh/CeZrO 2 steam reforming catalyst was prepared, exhibiting complete ethanol conversion (>99 %) and high hydrogen selectivity (> 62 %).…”

Gas‐to‐liquids processes: Preface

“…These nano-structures are distinct from the bulk with respect to their chemical properties, structural properties (including defects-steps, edges, kinks), and textural properties. [8] The H 2 −D 2 isotopic homomolecular exchange reaction can assess the diffusion rate of chemisorbed and physisorbed hydrogen species. [9] Hydrogen and deuterium dissociatively adsorb on the surface of Co/Al 2 O 4 and then associatively desorb as HD-the Bonhoeffer-Farkas reaction mechanism.…”

“…Hydrogenation reactions are optimal with a broad distribution of metal catalyst particles. These nano‐structures are distinct from the bulk with respect to their chemical properties, structural properties (including defects—steps, edges, kinks), and textural properties . The isotopic homomolecular exchange reaction can assess the diffusion rate of chemisorbed and physisorbed hydrogen species .…”