The utilization of fossil fuels has enabled an unprecedented era of prosperity and advancement of well-being for human society. However, the associated increase in anthropogenic carbon dioxide (CO2) emissions can negatively affect global temperatures and ocean acidity. Moreover, fossil fuels are a limited resource and their depletion will ultimately force one to seek alternative carbon sources to maintain a sustainable economy. Converting CO2 into value-added chemicals and fuels, using renewable energy, is one of the promising approaches in this regard. Major advances in energy-efficient CO2 conversion can potentially alleviate CO2 emissions, reduce the dependence on nonrenewable resources, and minimize the environmental impacts from the portions of fossil fuels displaced. Methanol (CH3OH) is an important chemical feedstock and can be used as a fuel for internal combustion engines and fuel cells, as well as a platform molecule for the production of chemicals and fuels. As one of the promising approaches, thermocatalytic CO2 hydrogenation to CH3OH via heterogeneous catalysis has attracted great attention in the past decades. Major progress has been made in the development of various catalysts including metals, metal oxides, and intermetallic compounds. In addition, efforts are also put forth to define catalyst structures in nanoscale by taking advantage of nanostructured materials, which enables the tuning of the catalyst composition and modulation of surface structures and potentially endows more promising catalytic performance in comparison to the bulk materials prepared by traditional methods. Despite these achievements, significant challenges still exist in developing robust catalysts with good catalytic performance and long-term stability. In this review, we will provide a comprehensive overview of the recent advances in this area, especially focusing on structure-activity relationship, as well as the importance of combining catalytic measurements, in situ characterization, and theoretical studies in understanding reaction mechanisms and identifying key descriptors for designing improved catalysts.

Recent Advances in Carbon Dioxide Hydrogenation to Methanol via Heterogeneous Catalysis.

The diesel oxidation catalyst (DOC) has been part of diesel exhaust systems since regulations were introduced to limit the amount of harmful emissions released to the environment from diesel engines. The DOC primary functions are oxidation of CO, unburned hydrocarbons, and NO, while active hydrocarbon oxidation can also be used to generate exotherms required for downstream components. This review will describe work that has attempted to understand the reactions, both desired and undesired, that occur over the catalyst. First, the history, configuration, and components of the DOC will be discussed, followed by in-depth coverage of the fundamental reactions that occur over a DOC, including reaction mechanisms, reaction inhibition, and other reactivity effects. Finally, DOC deactivation mechanisms and their effects on the DOC are described. While there is a lot of research literature regarding Pt- and Pd-based catalysts for many different reaction schemes, this review tries to highlight work most relevant to...

Diesel Oxidation Catalysts

Reactor technologies for biodiesel production and processing: a review.

CO2 hydrogenation to methanol over Cu/ZrO2 catalysts: Effects of zirconia phases

The effects of the most largely employed preparation methods (i.e . , coprecipitation with sodium bicarbonate, complexation with citric acid, gel-oxalate coprecipitation) on the structure and catalytic behaviour of Cu-Zn-Zr systems for methanol synthesis from hydrogenation of carbon dioxide have been studied. The characterization data of the dried, calcined and reduced catalysts showed that the physico-chemical properties can be controlled by varying composition and preparation method. The catalyst obtained by the gel-coprecipitation procedure showed the highest catalytic activity in the T R range 453–513 K, 3.0 MPa and 10,000 h −1 , due to a superior functionality in the CO 2 and H 2 activation. An adequate balance between metal and oxide surface sites, in correspondence of a well defined particle size, was proposed to be crucial to design active and selective catalysts for such reaction. The good performance of the gel-oxalate coprecipitated catalyst was confirmed by an endurance test (≈200 h), in which a constant and remarkable methanol space–time-yield value of 1200 g kg cat −1  h −1 at ≈10% CO 2 conversion was obtained ( T R , 513 K; P R , 3.0 MPa).

The changing nature of the active site of Cu-Zn-Zr catalysts for the CO2 hydrogenation reaction to methanol

CO2 hydrogenation to methanol over Cu/ZnO nanocatalysts prepared via a chitosan-assisted co-precipitation method

Biodiesel production from waste cooking oil in a microtube reactor

Biodiesel synthesis using heterogeneous catalyst in a packed-microchannel

Separation of concentrated platinum(IV) and rhodium(III) in acidic chloride solution via liquid–liquid extraction using tri-octylamine

A continuous packed-bed reactor was applied for the synthesis of 5-HMF via dehydration of fructose. Cation exchange rasin functionalized with sulfonic acid groups; -HSO3 was used as catalyst. 1-methyl-2-pyrrolidinone (NMP) was used as aqueous solvent to partially substitute water. A biphasic system with methyl isobutyl ketone (MIBK) as organic solvent was applied to enhance the transfer of 5-HMF from aqueous phase. Effects of reaction temperature (90–120 °C), residence time (10–60 min), water content in the aqueous phase (30–100 %wt.), and organic-to-aqueous ratio (1:1–4:1) on the conversion of fructose, %yield and selectivity of 5-HMF, and extraction ratio were investigated. High yield of 5-HMF was obtained with increasing reaction temperature or reaction time. Adding NMP enhanced the fructose conversion and selectivity toward 5-HMF to 91.67% and 99.76% at 120 °C, residence time of 30 min, NMP-to-water ratio of 7:3, and organic-to-aqueous ratio of 4:1, while the extraction ratio was 81.83%.

Attasak Jaree

Papers

CO2 hydrogenation to methanol over Cu/ZnO nanocatalysts prepared via a chitosan-assisted co-precipitation method

Biodiesel production from waste cooking oil in a microtube reactor

Biodiesel synthesis using heterogeneous catalyst in a packed-microchannel

Separation of concentrated platinum(IV) and rhodium(III) in acidic chloride solution via liquid–liquid extraction using tri-octylamine

Synthesis of 5-hydroxymethylfurfural (5-HMF) from fructose over cation exchange resin in a continuous flow reactor