Thermochemical Water-Splitting (TCWS) is a promising approach for generating clean hydrogen (H₂) by employing the waste heat originating from different sources. High-temperature requirements and temperature swing approach hinder the widespread adoption of TCWS for clean hydrogen production. This study explores ceria nanorods (CeNRs) as a potential solution for overcoming these limitations. Herein, we report, the TCWS in a fixed bed reactor using CeNRs at low and constant temperature of 400 °C. We systematically explore the influence of synthesis parameters on the resulting CeNRs, including the selection of ceria precursor, effect of calcination, and their impact in TCWS. It was found that CeNRs prepared using cerium chloride as the precursor exhibited enhanced TCWS activity, resulting significantly higher total H₂ yield 4.74 mL/g, at a constant temperature of 400 °C in three redox cycles. Moreover, X-ray Photoelectron Spectroscopy (XPS) analysis confirms the presence of both Ce³⁺ and Ce⁴⁺ states within the structure, with Ce³⁺ constituting approximately 30 % and Ce⁴⁺ accounting for approximately 70 % of the total cerium content. Additionally, Raman spectroscopy corroborates the presence of a higher concentration of oxygen vacancy which are beneficial for increasing the hydrogen production. We demonstrate that ceria in its nanorod structure having exposed higher proportions of (110) and (100) planes and higher concentration of oxygen vacancies is beneficial for lowering TCWS temperature as well as increasing the hydrogen yield.

Herein, the effect of the Ru:Ni bimetallic composition in dual-function materials (DFMs) for the integrated CO2 capture and methanation process (ICCU-Methanation) is systematically evaluated and combined with a thorough material characterization, as well as a mechanistic (in-situ diffuse reflectance infrared fourier-transform spectroscopy (in-situ DRIFTS)) and computational (computational fluid dynamics (CFD) modelling) investigation, in order to improve the performance of Ni-based DFMs. The bimetallic DFMs are comprised of a main Ni active metallic phase (20 wt%) and are modified with low Ru loadings in the 0.1–1 wt% range (to keep the material cost low), supported on Na2O/Al2O3. It is shown that the addition of even a very low Ru loading (0.1–0.2 wt%) can drastically improve the material reducibility, exposing a significantly higher amount of surface-active metallic sites, with Ru being highly dispersed over the support and the Ni phase, while also forming some small Ru particles. This manifests in a significant enhancement in the CH4 yield and the CH4 production kinetics during ICCU-Methanation (which mainly proceeds via formate intermediates), with 0.2 wt% Ru addition leading to the best results. This bimetallic DFM also shows high stability and a relatively good performance under an oxidizing CO2 capture atmosphere. The formation rate of CH4 during hydrogenation is then further validated via CFD modelling and the developed model is subsequently applied in the prediction of the effect of other parameters, including the inlet H2 concentration, inlet flow rate, dual-function material weight, and reactor internal diameter.

Urbanization and industrialization have significantly increased the demand for energy, predominantly sourced from nonrenewable fossil fuels such as natural gas, coal, and oil. Biomass-based biofuel has been considered as a suitable and sustainable option to suffice the growing needs. Among several biomass conversion pathways, thermochemical route through pyrolysis has received a lot of attention due to a good yield of liquid bio-oil and the direct conversion of biomass to value-added chemicals. This chapter describes the compositional structure of biomass and compares the physical, chemical, biochemical, and thermochemical techniques used for biomass conversion into useful products. The thermochemical pyrolysis process and the liquid bio-oil obtained as product are discussed to analyze its closeness in terms of compatibility with conventional fuel. Though pyrolytic bio-oil is produced in sufficient quantity, it is not suitable to replace the available nonrenewable energy resources due to the presence of high oxygen functionalities. Therefore, upgradation of this bio-oil is necessary to meet commercial needs and replace conventional energy sources. Various pyrolysis oil upgrading methods to produce high-quality fuel and chemicals with special emphasis on the hydrodeoxygenation reaction are discussed here. This chapter provides a special emphasis on the hierarchical zeolites, which are found to be promising catalysts due to their lesser deactivation and high reaction rate as compared with commercial zeolites.