Impact of Support (MCF, ZrO2, ZSM-5) on the Efficiency of Ni Catalyst in High-Temperature Conversion of Lignocellulosic Biomass to Hydrogen-Rich Gas

The main objective of this work was to evaluate an impact of a support on the efficiency of nickel catalysts in the high-temperature conversion of lignocellulosic biomass to hydrogen-rich gas. The most important parameters influencing catalytic performance of the catalysts were identified. The properties of three materials (ZSM-5, ZrO2, and MCF (mesostructured cellular foam)) used as a support differing in surface acidity, surface area, pore structure, ability to interact with an active phase, and resistance to coking, have been studied. The results revealed that Ni/MCF, characterized by large pore size and pore volume, low acidity, small NiO crystallites size, and moderate interaction with the active phase, is the most efficient among studied catalysts, while an application of Ni on ZSM-5 support with high-acidity was not beneficial. The results suggest that structure of the support, in particular larger pore size and a better contact between an active phase and reaction intermediates, play an important role in the formation of gaseous products during thermal decomposition of lignocellulosic feedstock. On the other hand, high acidity of the support did not increase the formation of large amounts of hydrogen-rich gaseous products

Modification of Ni/ZrO2 catalyst by selected rare earth metals as a promising way for increase in the efficiency of thermocatalytic conversion of lignocellulosic biomass to hydrogen-rich gas

The main goal of this work was the evaluation of the effect of modification of zirconia by selected rare earth metals (praseodymium, yttrium and gadolinium) on the activity of nickel catalyst in the high temperature conversion of lignocellulosic biomass to hydrogen-rich gas. An influence of type of dopant, its content and introduction method was studied. The obtained results revealed that the modification of catalysts allowed for noticeable increase the efficiency of hydrogen-rich gas production in the high temperature conversion of lignocellulosic feedstock. The highest activity among studied catalysts was observed for nickel supported on zirconium oxide modified by praseodumium via sol-gel method. The performed experiments (XRD, XPS, TEM, TPR, TPD-NH3, TG-DTA-MS and BET) indicated that an increase in the activity of investigated catalysts can be not only related with larger surface area, pore volume and higher acidity, but also size and location of active phase crystallites, susceptibility of nickel oxide to the reduction and contribution of Pr3+ ions in zirconia lattice.Web of Science276art. no. 11811

Impact of Zr Incorporation into the Ni/AlSBA-15 Catalyst on Its Activity in Cellulose Conversion to Hydrogen-Rich Gas

This work focused on the investigation of the effect of zirconium incorporation into the structure of the Ni/AlSBA-15 catalyst on its performance in high-temperature conversion of cellulose (the main component of lignocellulosic feedstock) to hydrogen-rich gas. The modified supports were prepared by direct incorporation of zirconium and impregnation methods. The obtained results exhibited that introduction of zirconium into the structure of Ni/AlSBA-15 allowed for a considerable increase in the amount of hydrogen produced in the studied process in comparison to unmodified Ni/AlSBA-15 material. The characterization of physicochemical properties of the investigated materials (X-ray diffraction, scanning electron microscopy–energy-dispersive X-ray spectroscopy, time-of-flight secondary ion mass spectrometry, temperature-programmed reduction, temperature-programmed desorption of ammonia, etc.) showed that the preparation of mesoporous Ni/ZrAlSBA-15 with the use of the direct synthesis method led to obtaining the catalyst with a higher surface area and pore volume and smaller crystallites of an active phase in comparison to the material containing nickel supported on ZrAlSBA-15 with zirconium introduced by impregnation. Despite that the mesoporous catalyst prepared by impregnation possessed higher acidity, its structure underwent partial collapse during the preparation procedure