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C2+ hydrocarbons, especially C2+ olefins, as important basic chemical raw materials, mainly come from petroleum cracking. With the increasing scarcity of petroleum resources, the search for new olefins production routes has become the focus of research, and the production of olefins by the oxidative coupling of methane (OCM) process has attracted extensive attention. The OCM route is an important alternative to the production of olefins from petroleum resources and is also an important direction for the development of efficient and clean utilization of natural gas. In this paper, the mechanism, catalysts, and other key factors for the production of olefins by methane oxidative coupling are reviewed. The mechanism of OCM, including the reaction pathway and the formation of intermediate products, is introduced. Then, commonly used catalysts, such as alkali metal/alkaline earth metal oxides, rare earth metal oxides, composite metal oxides with special structures, and classical catalysts Mn/Na2WO4/SiO2, and their mechanisms of action in the reaction are discussed. In addition, the application of chemical looping oxidative coupling of methane (CLOCM) in olefin production is also investigated, which is a promising alternative way due to the high selectivity of olefins and the low cost of catalysts owing to the excellent performance of the catalyst recycling. These studies will help to further understand the mechanism of OCM for olefin production and provide guidance and support for applications in related fields. [ABSTRACT FROM AUTHOR]

A conductive polymer‐based photosynthetic biohybrid is constructed to enhance biological nitrogen fixation by increasing nitrogenase activity in the non‐photosynthetic bacterium Azotobacter Chroococcum (A. Chroococcum). The light‐harvesting cationic poly(fluorene‐alt‐phenylene) (PFP) electrostatically binds to the surface of the bacteria and possesses satisfactory conductivity to facilitate electron transfer to the bacterium, promoting the nitrogen fixation pathway through redox proteins on the surface of the bacteria when under illumination. Therefore, the nitrogenase activity, hydrogen, NH4+‐N and L‐amino acids production are increased by 260 %, 37 %, 44 %, and 47 %, respectively. The expression levels of nifD and nifK encoding molybdenum‐iron (MoFe) protein and relevant nitrogen‐fixing proteins are up‐regulated. These photoactive conductive polymer‐bacteria biohybrids provide a new method for improving the biological nitrogen fixation capability of non‐photosynthetic nitrogen‐fixing bacteria. [ABSTRACT FROM AUTHOR]

To reveal the effect of torrefaction pretreatment on pyrolysis and gasification reactivity of biomass, corn cob was first subjected to torrefaction pretreatment in a fixed-bed reactor at various reaction temperatures. The pyrolysis reactivity, kinetics, and gasification reactivity of torrefied corn cob were systematically assessed by various methods, proving that torrefaction pretreatment has a substantial influence on the physicochemical properties of corn cobs. The O/C and H/C molar ratios of corn cobs considerably drop with the increasing torrefaction temperature, and their higher heat-ing value (HHV) and energy density rise as well. It is found that torrefaction improves the pyrolysis reactivity of corn cobs because hemicellulose degradation is more severe than cellulose degradation during torrefaction, resulting in an increase in the percentage of cellulose in torrefied corn cobs. However, the severe depolymerization, polycondensation, and carbonization reaction during torre-faction of corn cobs at 280–300 °C can lead to a significant decline in the pyrolysis reactivity of corn cobs. Torrefaction pretreatment increases the pyrolysis activation energy of corn cobs, in addition to decreasing the char gasification reactivity of corn cob. The average char gasification reactivity of corn cobs drops when torrefaction severity increases. The passivation of active sites on the char surface may cause condensation and carbonation reactions of corn cobs during torrefaction. These findings provide new sights into the reasonable design of efficient torrefaction methods for appli-cation prior to pyrolysis and gasification of biomass. [ABSTRACT FROM AUTHOR]

A series of small molecules containing alternative multiple donor and acceptor units have been designed and synthesized. These small molecules introduce diketopyrrolopyrrole (DPP) and difluorobenzotriazole (DFBZ) as acceptor units and different donor cores with the intention to modulate intermolecular and intramolecular interactions and ultimately improve the power conversion efficiency (PCE). The structure–property relationship has been systematically investigated through exploring the effect of the electron-donating ability of the central donor unit on optoelectronic properties, crystallinity and morphology. As a result, IDTTFD has the strongest absorption in the visible region and appropriate energy levels. The organic solar cells based on IDTTFD/PC61BM achieve the highest PCE of 7.06% with a Voc of 0.86 V, a Jsc of 14.08 mA cm−2, and a FF of 58%. [ABSTRACT FROM AUTHOR]

Abstract: Two different non‐fullerene small‐molecule acceptors, m‐PIB and p‐PIB, based on 9,9′‐bifluorenylidene (BF) and perylene diimide (PDI) were designed and synthesized. Four β‐substituted PDIs were linked to BF in different positions. Based on DFT analysis, derivative p‐PIB exhibited reduced intramolecular twisting between the PDI moieties, more delocalized wave function, and sufficiently wider π‐electron delocalization than that of m‐PIB. The absorption ability of p‐PIB was enhanced due to increased intermolecular interactions. By blending p‐PIB with poly{4,8‐bis[5‐(2ethylhexyl)thiophen‐2‐yl]benzo[1,2‐b:4,5‐b′]dithiophene‐co‐3‐fluorothieno[3,4‐b]‐thiophene‐2‐carboxylate} (PTB7‐Th), organic solar cells (OSCs) based on p‐PIB obtained a maximum power conversion efficiency of 5.95 % without any treatments. Due to the improved and balanced hole and electron mobilities, the short‐circuit current and fill factor of OSCs based on PTB7‐Th and p‐PIB were significantly increased. The AFM and TEM results revealed that the PTB7‐Th:p‐PIB film had favorable nanoscale phase separation and formed a bicontinuous interpenetrating network. [ABSTRACT FROM AUTHOR]

• H 2 SO 4 loading can lower the pyrolysis temperature of biomass from 500 to 300 °C. • The formation of light oxygenates, permanent gases and char was suppressed. • 50–60 wt% biomass was converted into anhydrosugars and their dehydrated products. • The reaction pathways for pyrolysis of H 2 SO 4 -loaded biomass at 300 °C were proposed. Fast pyrolysis is a promising method for the production of liquid fuels and chemicals from lignocellulosic biomass. However, the catalytic effects of inherent alkali and alkaline earth metals and the high temperature used for the fast pyrolysis of biomass can drastically promote uncontrolled C-C/C-O bond cleavages and polycondensation reactions, resulting in the formation of considerable amounts of undesired light oxygenated organic compounds, permanent gases and char. Here, we demonstrate that H 2 SO 4 loading can lower the pyrolysis temperature of biomass from 500 to 300 °C with higher yield of platform chemicals. The pyrolysis of H 2 SO 4 -loaded biomass at 300 °C is capable of selectively breaking C-O bonds in polysaccharides and effectively suppressing the formation of light oxygenated organic compounds, permanent gases and char. Approximately 50–60 wt% biomass feedstocks are primarily converted into anhydrosugars (mainly levoglucosan and xylosan) and their dehydrated products (mainly levoglucosenone and furfural). It is inferred that H 2 SO 4 combined with the inherent alkali and alkaline earth metals (AAEM) in raw biomass can simultaneously inhibits the catalytic functions of AAEM and H 2 SO 4 for achieving oriented conversion of hemicellulose and cellulose at low temperature. This study provides a very simple, atom-economical and energy-efficient pyrolytic strategy for enhancing the production of platform chemicals from biomass. [ABSTRACT FROM AUTHOR]

• Efficient sugar release from softwood is hampered by its recalcitrant nature. • Ultrasonic and microwave assisted organosolv pretreatment enhanced pine pyrolysis. • The formation pathway of pyrolytic sugar and by-products were thoroughly analyzed. Efficient fermentable sugar release from softwood biomass is considerably hampered by the recalcitrant nature of its plant cell wall. Here, we reported an ultrasonic and microwave assisted ethylene glycol pretreatment coupled with fast pyrolysis to make total utilization of softwood (pine sawdust) for pyrolytic sugar (levoglucosan), hemicellulosic sugar and phenol production. Compared with oil bath heating, fractionation of pine sawdust into cellulose rich fraction, hemicellulosic sugars and organosolv lignin was enhanced drastically after applying ultrasonic and microwave heating. Whereas, ultrasonic radiation prior to microwave heating turned out to slightly inhibit the fractionation due to oxygenation of sulfuric acid. Mechanistic insight into levoglucosan formation pathway revealed that microwave heating promoted the cleavage of covalent bonds, aromatic ether linkages and glycosidic bonds in lignocellulose, leading to significant improvement in biomass recalcitrance alleviation as well as alkaline and alkaline earth metal removal. This considerably facilitated the heterolytic cleavage of cellulose into levoglucosan, while inhibiting the formation of microorganism inhibitors (e.g. carboxylic acids and phenols) and other light oxygenates in the pyrolysate. Levoglucosan yield exhibited a drastic increase from 3.53 (pine sawdust) to 48.13 wt.% via single microwave heating at 240 W, which was further enhanced with increasing microwave power. Hemicellulosic sugar derived from organosolvolysis and phenol from fast pyrolysis of organosolv lignin also showed an increase in yields with increasing pretreatment severity. Ethylene glycol pretreatment via single microwave heating at 480 W was a preferable process for achieving high yields of levoglucosan (55.87 wt.%), hemicellulosic sugars (19.96 wt.%) and phenols (14.04 wt.%). These findings help to provide an efficient process for maximizing the conversion of recalcitrant softwood for the production of fermentable sugars and phenols. [ABSTRACT FROM AUTHOR]