A novel Ni–zeolite–biochar green catalyst: optimization of composition and preparation strategy revealed by TPR, TPD, and XPS

The development in green hydrogenation technology depends on the production of robust and reasonably priced catalyst supports. This study synthesized and optimized a novel Ni-zeolite-biochar hybrid catalyst, improved by changes in composition, method of synthesis, and metal loading. The catalyst was developed using commercially obtained mordenite zeolite with a high-silica framework-type material known for its strong acidity and thermal stability, and biochar derived from date pit powder through controlled pyrolysis, providing acidity and surface oxygenation functionalities, respectively. The investigation of reducibility, metal dispersion, metal support interaction strength and electronic interactions of the material was conducted using temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS), thereby fully describing it. Out of different nickel loading (5 %,15 %,25 %), 15 % was identified as optimal. Similarly, the effects of zeolite content, impregnation order, and the roles of wet impregnation and co-impregnation in catalyst reducibility were critically analyzed. The best formulation of Nickel zeolite biochar (NZB) exhibited a low reduction temperature (Tmax = 390 °C), high hydrogen consumption (7135.2 μmolg-1), medium metal-support interaction, and high dispersion (63.27 %). Compared to conventional Ni-based catalysts such as Ni/Al₂O₃ and Ni/SiO₂, the hybrid system demonstrated an improved reducibility and high metal dispersion. The robustness of the system was enhanced by the acidity of the zeolite and the oxygenation properties of the biochar together. The Ni 2p binding energy exhibited a positive shift on the XPS test, therefore confirming a strong electrical link between the metal and the substrate. This work presents a fresh, environmentally friendly, flexible catalytic support system that enhances nickel dispersion and reducibility. This study will provide the foundation for catalytic applications including selective hydrogenations. The catalytic relevance of the optimized NZB system was demonstrated through its successful application in 1,3-butadiene selective hydrogenation, achieving 100 % conversion with excellent deactivation resistance.