The demand for fossil derivate fuels and chemicals has increased, augmenting concerns on climate change, global economic stability, and sustainability on fossil resources. Therefore, the production of fuels and chemicals from alternative and renewable resources has attracted considerable and growing attention. Ethanol is a promising biofuel that can reduce the consumption of gasoline in the transportation sector and related greenhouse gas (GHG) emissions. Lignocellulosic biomass is a promising feedstock to produce bioethanol (cellulosic ethanol) because of its abundance and low cost. Since the conversion of lignocellulose to ethanol is complex and expensive, the cellulosic ethanol price cannot compete with those of the fossil derivate fuels. A promising strategy to lower the production cost of cellulosic ethanol is developing a biorefinery which produces ethanol and other high-value chemicals from lignocellulose. The selection of such chemicals is difficult because there are hundreds of products that can be produced from lignocellulose. Multiple reviews and reports have described a small group of lignocellulose derivate compounds that have the potential to be commercialized. Some of these products are in the bench scale and require extensive research and time before they can be industrially produced. This review examines chemicals and materials with a Technology Readiness Level (TRL) of at least 8, which have reached a commercial scale and could be shortly or immediately integrated into a cellulosic ethanol process.

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A review on commercial-scale high-value products that can be produced alongside cellulosic ethanol.

Commercial and environmental benefits have made carbon dioxide (CO2) methanation one of the topmost research projects all over the world both at the pilot plant and commercial scale. Mitigation of CO2 via carbon capture and storage (CCS) routes have less motivation from a commercial point of view. Therefore, an integrated system is of paramount importance to convert CO2 into value-added products such as methane (CH4) using solar energy (photosynthesis) or surplus electrical energy in hydrolysis for production of reactant hydrogen to use in CO2 methanation. To date, great efforts have been made to investigate both the reaction mechanism and catalysts development for methanation. Here in this review, up to date references have been cited, which are aimed at giving researchers a comprehensive overview of CO2 methanation with respect to the recent advancements in reaction mechanism, catalytic materials, and the novel combination of metal active phase and its synergy. Both thermochemical and electrochemical ro...

Recent Advancements, Fundamental Challenges, and Opportunities in Catalytic Methanation of CO2

The implementation of biorefineries based on lignocellulosic materials as an alternative to fossil-based refineries calls for efficient methods for fractionation and recovery of the products. The focus for the biorefinery concept for utilisation of biomass has shifted, from design of more or less energy-driven biorefineries, to much more versatile facilities where chemicals and energy carriers can be produced. The sugar-based biorefinery platform requires pretreatment of lignocellulosic materials, which can be very recalcitrant, to improve further processing through enzymatic hydrolysis, and for other downstream unit operations. This review summarises the development in the field of pretreatment (and to some extent, of fractionation) of various lignocellulosic materials. The number of publications indicates that biomass pretreatment plays a very important role for the biorefinery concept to be realised in full scale. The traditional pretreatment methods, for example, steam pretreatment (explosion), organosolv and hydrothermal treatment are covered in the review. In addition, the rapidly increasing interest for chemical treatment employing ionic liquids and deep-eutectic solvents are discussed and reviewed. It can be concluded that the huge variation of lignocellulosic materials makes it difficult to find a general process design for a biorefinery. Therefore, it is difficult to define “the best pretreatment” method. In the end, this depends on the proposed application, and any recommendation of a suitable pretreatment method must be based on a thorough techno-economic evaluation.

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Pretreatment for biorefineries: a review of common methods for efficient utilisation of lignocellulosic materials

Adsorption of CO2 from flue gas by novel seaweed-based KOH-activated porous biochars

Carbon capture from large sources and ambient air is one of the most promising strategies to curb the deleterious effect of greenhouse gases. Among different technologies, CO2 adsorption has drawn widespread attention mostly because of its low energy requirements. Considering that water vapor is a ubiquitous component in air and almost all CO2-rich industrial gas streams, understanding its impact on CO2 adsorption is of critical importance. Owing to the large diversity of adsorbents, water plays many different roles from a severe inhibitor of CO2 adsorption to an excellent promoter. Water may also increase the rate of CO2 capture or have the opposite effect. In the presence of amine-containing adsorbents, water is even necessary for their long-term stability. The current contribution is a comprehensive review of the effects of water whether in the gas feed or as adsorbent moisture on CO2 adsorption. For convenience, we discuss the effect of water vapor on CO2 adsorption over four broadly defined groups of materials separately, namely (i) physical adsorbents, including carbons, zeolites and MOFs, (ii) amine-functionalized adsorbents, and (iii) reactive adsorbents, including metal carbonates and oxides. For each category, the effects of humidity level on CO2 uptake, selectivity, and adsorption kinetics under different operational conditions are discussed. Whenever possible, findings from different sources are compared, paying particular attention to both similarities and inconsistencies. For completeness, the effect of water on membrane CO2 separation is also discussed, albeit briefly.

Understanding the Effect of Water on CO 2 Adsorption

In the last few decades of industrialization, the concentration of CO2 in the atmosphere had increased rapidly. Different organizations have invested considerable funds in research activities worldwide for CO2 capture and storage. To date, significant work has been done and various technologies have been proposed for CO2 capture and storage. Both adsorption and absorption are promising techniques for CO2 capture, but low-temperature adsorption processes using solid adsorbents are the prevailing technique nowadays. In this review paper, a variety of adsorbents such as carbonaceous materials, dry alkali metal-based sorbents, zeolites, metal–organic frameworks (MOFs) and microporous organic polymers (MOPs) have been studied. Various methods of chemical or physical modification and the effects of supporting materials have been discussed to enhance CO2 capture capacity of these adsorbents. Low-temperature (<100 °C) adsorption processes for CO2 capture are critically analyzed and concluded on the basis of information available so far in the literature. All the information in CO2 adsorption using different routes has been discussed, summarized and thoroughly presented in this review article. The most important comparative study of relatively new material MOFs and MOPs is carried out between the groups and with other sorbent as well.

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Feasibility of CO2 adsorption by solid adsorbents: a review on low-temperature systems

The effect of Bi promoter on vanadium phosphate catalysts synthesized via sesquihydrate route

Effect of CO2 adsorbents on the Ni‐based dual‐function materials for CO2 capturing and in situ methanation

Synthesis and characterisation of vanadyl pyrophosphate catalysts via vanadyl hydrogen phosphate sesquihydrate precursor

The aim of this study was to verify the ability of nickel-impregnated palm shell activated carbon (PSAC) for CO2 adsorption and compare its performance with the chemically and physically activated PSAC. Sodium hydroxide and CO2 were used as activating agents for chemical and physical activation, respectively. Nickel nitrate hexahydrate (Ni(NO3)2·6H2O) was used as a precursor for metal impregnation. The effect of different chemical loadings (NaOH: 20–50 wt%), metal impregnation (Ni(NO3)2·6H2O: 16–28 wt%), and heat treatment time (1–4 h) was studied as parameters. Adsorption capacity was calculated using breakthrough graphs. The effect of humidity on CO2 adsorption and desorption of CO2 was also investigated in this study. The results revealed that chemically modified PSAC yields the highest adsorption capacity (48.2 mg/g) compared to other methods of activation. Interestingly, it was found that the adsorption capacity of nickel-impregnated PSAC was similar to other types of metal-impregnated activated carb...

Loong Kong Leong

Papers

Feasibility of CO2 adsorption by solid adsorbents: a review on low-temperature systems

The effect of Bi promoter on vanadium phosphate catalysts synthesized via sesquihydrate route

Effect of CO2 adsorbents on the Ni‐based dual‐function materials for CO2 capturing and in situ methanation

Synthesis and characterisation of vanadyl pyrophosphate catalysts via vanadyl hydrogen phosphate sesquihydrate precursor

CO2 Adsorption by Modified Palm Shell Activated Carbon (PSAC) Via Chemical and Physical Activation and Metal Impregnation