Wheat-Straw-Derived Activated Biochar as a Renewable Support of Ni-CeO2 Catalysts for CO2 Methanation

Insights into Enhanced Peroxydisulfate Activation with B and Fe Co-Doped Biochar from Bark for the Rapid Degradation of Guaiacol

A boron and iron co-doped biochar (B-Fe/biochar) from Masson pine bark was fabricated and used to activate peroxydisulfate (PDS) for the degradation of guaiacol (GL). The roles of the dopants and the contribution of the radical and non-radical oxidations were investigated. The results showed that the doping of boron and iron significantly improved the catalytic activity of the biochar catalyst with a GL removal efficiency of 98.30% within 30 min. The degradation of the GL mainly occurred through the generation of hydroxyl radicals (·OHs) and electron transfer on the biochar surface, and a non-radical degradation pathway dominated by direct electron transfer was proposed. Recycling the B-Fe/biochar showed low metal leaching from the catalyst and satisfactory long-term stability and reusability, providing potential insights into the use of metal and non-metal co-doped biochar catalysts for PDS activation.

A Model for the Flow Distribution in Dual Cell Density Monoliths

Monoliths are promising as catalytic structured supports due to their many operational advantages. Compared to pellets, monoliths offer low backpressure and good heat distribution, even at high flow rates. There is interest in the industry for improving temperature control in highly exothermic systems, such as the catalytic hydrogenation of CO2 for e-fuels synthesis. In this context, novel substrate shapes, such as non-homogeneous cell density monoliths, show good potential; however, to date, they have only been sparsely described. This work focuses on a dual cell density substrate and uses a computational model of a straight-channel monolith with two concentric regions to analyze its flow distribution. The central (core) and peripheral (ring) regions of the substrate differ in cell density in order to obtain a non-homogeneous cross-section. The model is validated against classical data in the literature and theoretical equations. Then, the flow fraction passing through each region of the substrate is registered. Several flow rates, core sizes and combinations of apparent permeabilities are tested. According to the results, the flow distribution depends only on the monolith geometrical features and not on the flow rate. A model for this phenomenon is proposed. The model accurately predicted the flow fraction passing through each region of the monolith for all the cases analyzed.

The Route from Green H2 Production through Bioethanol Reforming to CO2 Catalytic Conversion: A Review

Currently, a progressively different approach to the generation of power and the production of fuels for the automotive sector as well as for domestic applications is being taken. As a result, research on the feasibility of applying renewable energy sources to the present energy scenario has been progressively growing, aiming to reduce greenhouse gas emissions. Following more than one approach, the integration of renewables mainly involves the utilization of biomass-derived raw material and the combination of power generated via clean sources with conventional power generation systems. The aim of this review article is to provide a satisfactory overview of the most recent progress in the catalysis of hydrogen production through sustainable reforming and CO2 utilization. In particular, attention is focused on the route that, starting from bioethanol reforming for H2 production, leads to the use of the produced CO2 for different purposes and by means of different catalytic processes, passing through the water–gas shift stage. The newest approaches reported in the literature are reviewed, showing that it is possible to successfully produce “green” and sustainable hydrogen, which can represent a power storage technology, and its utilization is a strategy for the integration of renewables into the power generation scenario. Moreover, this hydrogen may be used for CO2 catalytic conversion to hydrocarbons, thus giving CO2 added value.