Elucidation of metal and support effects during ethanol steam reforming over Ni and Rh based catalysts supported on (CeO2)-ZrO2-La2O3

We thank Dr Alan McCue from the Department of Chemistry, University of Aberdeen, for assisting in carrying out the TPO measurements. CRediT authorship contribution statement Marinela D. Zhurka: Investigation, Writing - original draft. Angeliki A. Lemonidou: Resources, Writing - review & editing. Panagiotis N. Kechagiopoulos: Conceptualization, Methodology, Writing - review & editing, Supervision.Peer reviewedPostprin

Kinetic analysis of the steam reforming of ethanol over Ni/SiO2 for the elucidation of metal dominated reaction pathways

Peer reviewedPostprin

Investigation of support effects during ethanol steam reforming over a Ni/Sepiolite catalyst

Peer reviewedPublisher PD

Catalytic Biomass Gasification in Supercritical Water and Product Gas Upgrading

The gasification of biomass with supercritical water, also known as SCWG, is a sustainable method of hydrogen production. The process produces a mixture of hydrogen, carbon oxides, and hydrocarbons. Upgrading this mixture through steam or dry reforming of hydrocarbons to create synthesis gas and then extra hydrogen is a viable way to increase hydrogen production from biomass. This literature review discusses combining these two processes and recent experimental work on catalytic SCWG of biomass and its model compounds and steam/dry reforming of produced hydrocarbons. It focuses on catalysts used in these processes and their key criteria, such as activity, selectivity towards hydrogen and methane, and ability to inhibit carbon formation and deposition. A new criterion is proposed to evaluate catalyst performance in biomass SCWG and the need for further upgrading via reforming, based on the ratio of hydrogen bound in hydrocarbons to total hydrogen produced during SCWG. The review concludes that most catalysts used in biomass SCWG trap a large proportion of hydrogen in hydrocarbons, necessitating further processing of the product stream

Acetic Acid Reforming over Rh Supported on La2O3/CeO2-ZrO2: Catalytic Performance and Reaction Pathway Analysis

Reforming of acetic acid was investigated on Rh supported on CeO2-ZrO2 modified with 3 wt H-2-rich gas and hardly formed coke. The low rate of coke formation is concluded to be related to the presence of redox-active oxygen limiting the concentration of coke precursors. Temperature-programmed O-18(2)) isotope exchange measurements showed that the La2O3 and Rh enhanced the mobility of lattice oxygen compared with that of the parent CeO2-ZrO2. Ketonization and decarboxylation of acetic acid are the dominating reactions over the latter up to 600 degrees C, whereas above 600 degrees C, steam reforming and water gas shift also contribute. Over 0.5 wt Rh on La2O3/CeO2-ZrO2, reforming and water gas shift reactions dominate, even below 300 degrees C, producing mostly H-2 and CO2. Using isotope labeling, it is shown that acetic acid adsorbs dissociatively on Rh, forming acetates, which sequentially decarboxylate and form surface methyl groups. The latter are in turn converted to CO, CO2, and H-2

Olefins from Biomass Intermediates: A Review

Over the last decade, increasing demand for olefins and their valuable products has prompted research on novel processes and technologies for their selective production. As olefins are predominately dependent on fossil resources, their production is limited by the finite reserves and the associated economic and environmental concerns. The need for alternative routes for olefin production is imperative in order to meet the exceedingly high demand, worldwide. Biomass is considered a promising alternative feedstock that can be converted into the valuable olefins, among other chemicals and fuels. Through processes such as fermentation, gasification, cracking and deoxygenation, biomass derivatives can be effectively converted into C2–C4 olefins. This short review focuses on the conversion of biomass-derived oxygenates into the most valuable olefins, e.g., ethylene, propylene, and butadiene

Catalytic Glycerol Hydrodeoxygenation under Inert Atmosphere: Ethanol as a Hydrogen Donor

Glycerol hydrodeoxygenation to 1,2-propanediol (1,2-PDO) is a reaction of high interest. However, the need for hydrogen supply is a main drawback of the process. According to the concept investigated here, 1,2-propanediol is efficiently formed using bio-glycerol feedstock with H2 formed in situ via ethanol aqueous phase reforming. Ethanol is thought to be a promising H2 source, as it is alcohol that can be used instead of methanol for transesterification of oils and fats. The H2 generated is consumed in the tandem reaction of glycerol hydrodeoxygenation. The reaction cycle proceeds in liquid phase at 220–250 °C and 1.5–3.5 MPa initial N2 pressure for a 2 and 4-h reaction time. Pt-, Ni- and Cu-based catalysts have been synthesized, characterized and evaluated in the reaction. Among the materials tested, Pt/Fe2O3-Al2O3 exhibited the most promising performance in terms of 1,2-propanediol productivity, while reusability tests showed a stable behavior. Structural integrity and no formation of carbonaceous deposits were verified via Temperature Programmed Desorption of hydrogen (TPD-H2) and thermogravimetric analysis of the fresh and used Pt/FeAl catalyst. A study on the effect of various operating conditions (reaction time, temperature and pressure) indicated that in order to maximize 1,2-propanediol productivity and yield, milder reaction conditions should be applied. The highest 1,2-propanediol yield, 53% (1.1 g1,2-PDO gcat−1·h−1), was achieved at a lower reaction temperature of 220 °C

Carbonate Looping For Intermediate Temperature Co2 Capture: Evaluating The Sorption Efficiency Of Mineral-Based Mgo Promoted With Caco3 And Alkali Nitrates

This work focused on enhancing the CO2 capture kinetics of magnesite-derived MgO via alkali nitrate and mineral CaCO3 promoters for its application in the Carbonate Looping technology at intermediate temperatures (≤400°C). Alkali salts had a prominent role by shifting into molten state to offer a favorable carbonation pathway and allow a significantly higher CO2 uptake than non-promoted MgO, while their synergy with CaCO3 bestowed even better sorption activity. MgCO3 and CaMg(CO3)2 were detected as the main carbonate products, with the latter exhibiting faster formation rate. The sorbent with CaCO3 and alkali salts to MgO molar ratios of 0.05 and 0.20 respectively attained an uptake of 7.2 moles CO2/kg of sorbent when exposed to a 30%CO2 flow at 300°C with only 6% activity loss after 50 carbonation cycles, proving the applicability of the materials. Despite the cyclic sorption activity loss due to sintering and dewetting, alkali salts redistribution enabled a stable performance under proper conditions