Carbon dioxide capture,utilization and storage(CCUS)eincluding conversion to valuable chemicals-is a challenging contemporary issue having multi-facets.The prospect to utilize carbon dioxide(CO_(2))as a feedstock for ...Carbon dioxide capture,utilization and storage(CCUS)eincluding conversion to valuable chemicals-is a challenging contemporary issue having multi-facets.The prospect to utilize carbon dioxide(CO_(2))as a feedstock for synthetic applications in chemical and fuel industries-through carboxylation and reduction reactions-is the subject of this review.Current statute of the heterogeneously catalyzed hydrogenation,as well as the photocatalytic and electrocatalytic activations of conversion of CO_(2) to value-added chemicals is overviewed.Envisaging CO_(2) as a viable alternative to natural gas and oil as carbon resource for the chemical supply chain,three stages of development;namely,(i)existing mature technologies(such as urea production),(ii)emerging technologies(such as formic acid or other single carbon(C1)chemicals manufacture)and(iii)innovative explorations(such as electrocatalytic ethylene production)have been identified and highlighted.A unique aspect of this review is the exploitations of reactions of CO2 ewhich stems from existing petrochemical plants-with the commodity petrochemicals(such as,methanol,ethylene and ethylene oxide)produced at the same or nearby complex in order to obtain value-added products while contributing also to CO_(2) fixation simultaneously.Exemplifying worldwide ethylene oxide facilities,it is recognized that they produce about 3 million tons of CO2 annually.Such a CO_(2) resource,which is already separated in pure form as a requirement of the process,should best be converted to a value-added chemical there avoiding current practice of discharging to the atmosphere.The potential utilization of CO_(2),captured at power plants,should also been taken into consideration for sustainability.This CO_(2) source,which is potentially a raw material for the chemical industry,will be available at sufficient quality and at gigantic quantity upon realization of on-going tangible capture projects.Products resulting from carboxylation reactions are obvious conversions.In addition,provided that enough s展开更多
Photosynthetic CO2 fixation is the ultimate source of organic carbon on earth and thus is essential for crop production and carbon sequestration, Ribulose-1,5-bis- phosphate carboxylase/oxygenase （Rubisco） catalyzes...Photosynthetic CO2 fixation is the ultimate source of organic carbon on earth and thus is essential for crop production and carbon sequestration, Ribulose-1,5-bis- phosphate carboxylase/oxygenase （Rubisco） catalyzes the first step of photosynthetic CO2 fixation. However, the extreme low carboxylation efficiency of Rubisco makes it the most attractive target for improving pho- tosynthetic efficiency. Extensive studies have focused on re-engineering a more efficient enzyme, but the effort has been impeded by the limited understanding of its structure-function relationships and the lack of an effi- cient selection system towards its activity. To address the unsuccessful molecular engineering of Rubisco, we developed an Escherichia coil-based activity-directed selection system which links the growth of host cell solely to the Rubisco activity therein. A Synechococcus sp. PCC7002 Rubisco mutant with E49V and D82G sub- stitutions in the small subunit was selected from a total of 15,000 mutants by one round of evolution. This mutant showed an 85% increase in specific carboxyla- tion activity and a 45% improvement in catalytic efficiency towards CO2. The small-subunit E49V mutation was speculated to influence holoenzyme catalysis through interaction with the large-subunit Q225. This interaction is conserved among various Rubisco from higher plants and Chlamydomonas reinhardtii. Knowledge of these might provide clues for engineering Rubisco from higher plants, with the potential of increasing the crop yield.展开更多
Both the photosynthetic light curves and CO2 curves of Juglans regia L. and Ziziphus jujuba Mill. var. spinosa in three seasons were measured using a LI-6400 portable photosynthesis system. The maximal net photosynthe...Both the photosynthetic light curves and CO2 curves of Juglans regia L. and Ziziphus jujuba Mill. var. spinosa in three seasons were measured using a LI-6400 portable photosynthesis system. The maximal net photosynthetic rate （Amax）, apparent quantum efficiency（φ）, maximal carboxylation rate （Vcmax） and water use efficiency （WUE） of the two species were calculated based on the curves. The results showed that Amax of J. regia reached its maximum at the late-season, while the highest values of Amax of Z. jujuba occurred at the mid-season. The Amax of J. regia was more affected by relative humidity （RH） of the atmosphere, while that of Z. jujuba was more affected by the air temperature. Light saturation point （LSP） and Light compensation point （LCP） of J. regia had a higher correlation with RH of the atmosphere, those of Z. jujuba, however, had a higher correlation with air temperature. Vcmax of both J. regia and Z. jujuba had negative correlation with RH of the atmosphere. WUE of J. regia would decrease with the rise of the air temperature while that of Z. jujuba increased. Thus it could be seen that RH, temperature and soil moisture had main effect on photosynthesis and WUE of J. regia and Z. jujuba. Incorporating data on the physiological differences among tree species into forest carbon models will greatly improve our ability to predict alterations to the forest carbon budgets under various environmental scenarios such as global climate change, or with differing species composition.展开更多
Photosynthetic rate (Pn) and the partitioning of noncyclic photosynthetic electron transport to photorespiration (Jo) in seedlings of four subtropical woody plants growing at three light intensities were studied in th...Photosynthetic rate (Pn) and the partitioning of noncyclic photosynthetic electron transport to photorespiration (Jo) in seedlings of four subtropical woody plants growing at three light intensities were studied in the summer time by measurements of chlorophyll fluorescence and CO2 exchange. Except Schima superba, an upper canopy tree species, the tree species Castanopsis fissa and two understory shrubs Psychotria rubra, Ardisia quinquegona had the highest Pn at 36% of sunlight intensity. The total photosynthetic electron transport rate (JF) and the ratio of Jo/JF were elevated in leaves under full sunlight. Jo/JF ratio reached 0.5-0.6 and coincided with the increasing of oxygenation rate of Rubisco (Vo), the activity of glycolate oxidase and photorespiration rate at full sunlight. It is suggested that an increasing partitioning proportion of photosynthetic electron transport to photorespiration might be one of the protective regulation mechanisms in forest plant under strong summer light and high temperature conditions.展开更多
Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under m...Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under mild reaction conditions （8 bar CO2, 25 ~C）. Styrene and propylene carbonates were formed with high yields （95% and 82%, respectively）. Catalytic performance of Cr-MIL-101 was compared with other MOFs： Fe-MIL-101, Zn-MOF-5 and HKUST-1, The catalytic properties of different quaternary ammonium bromides, Cr-MIL-101 as well as PW12/Cr-MIL-101 composite material have been assessed in oxidative carboxylation of styrene in the presence of both tert-butyl hydroperoxide and H202 as oxidants at 8-100bar CO2 and 25-80 ~C with selectivity to styrene carbonate up to 44% at 57% substrate conversion.展开更多
Carbon dioxide is a ubiquitous and inexpensive one-carbon source for chemical synthesis, and the efficient incorporation of CO2 into organic molecules is of widespread research interest both for economic and ecologica...Carbon dioxide is a ubiquitous and inexpensive one-carbon source for chemical synthesis, and the efficient incorporation of CO2 into organic molecules is of widespread research interest both for economic and ecological reasons. The methodologies to employ carbon dioxide as a single-carbon unit to construct molecules relevant for agrochemical and pharmaceutical research include many elegant approaches, including asymmetric transformations. Even though remarkable achievements have been made in the field of light-driven catalysis, especially photoredox catalysis, homogeneous light-driven catalytic carboxylation by employing CO2 as the key reagent has only become a subject of increasing attention in recent years. Therefore, this concise review will discuss the latest advances in this research area.展开更多
Effects of cerium （Ce^3＋） on photosynthetic characteristics were investigated by hydroponics under laboratory conditions when soybean seedlings were exposed to two levels of supplementary UV-B radiation. UV-B radia...Effects of cerium （Ce^3＋） on photosynthetic characteristics were investigated by hydroponics under laboratory conditions when soybean seedlings were exposed to two levels of supplementary UV-B radiation. UV-B radiation badly inhibited the photosynthesis in soybean seedling, leading to a reduction in net photosynthetic rate （Pn）, Hill reaction activity, light saturated photosynthetic rate （Ps） and apparent quanta yield （AQY）, as well as the CO2 and light saturated photosynthetic rate （Pro） and carboxulation efficiency （CE）. On the contrary, Ce obviously promoted the photosynthesis of plants by increasing Hill reaction activity, accelerating electron transport and photophosphorylation, and enhancing carboxylation efficiency. For Ce＋UV-B treatments, the values of photosynthetic parameters were still lower than those of the control, but obviously higher than those of UV-B treatment. The results indicated that Ce alleviated the inhibition of UV-B radiation on the photosynthesis in soybean seedling to a certain extent. In correlating of Pn with Hill activity, AQY and CE, we found that the changes of photosynthetic rate were mainly influenced by the regulating effect of Ce on Hill activity and AQY at low level （0.15 W/m^2） of UV-B radiation, but were dominated by the regulating effect of Ce on CE at high level （0.45 W/m^2）. Thus, Ce could regulate many aspects in photosynthesis of soybean seedling under UV-B stress. The regulating mechanism was close related with the dosage of UV-B radiation.展开更多
基金Authors gratefully acknowledge Hasan Arslan,Senior Process Consultant,PTTGC America,for the hindsight provided for matured and developing petrochemical processes.
文摘Carbon dioxide capture,utilization and storage(CCUS)eincluding conversion to valuable chemicals-is a challenging contemporary issue having multi-facets.The prospect to utilize carbon dioxide(CO_(2))as a feedstock for synthetic applications in chemical and fuel industries-through carboxylation and reduction reactions-is the subject of this review.Current statute of the heterogeneously catalyzed hydrogenation,as well as the photocatalytic and electrocatalytic activations of conversion of CO_(2) to value-added chemicals is overviewed.Envisaging CO_(2) as a viable alternative to natural gas and oil as carbon resource for the chemical supply chain,three stages of development;namely,(i)existing mature technologies(such as urea production),(ii)emerging technologies(such as formic acid or other single carbon(C1)chemicals manufacture)and(iii)innovative explorations(such as electrocatalytic ethylene production)have been identified and highlighted.A unique aspect of this review is the exploitations of reactions of CO2 ewhich stems from existing petrochemical plants-with the commodity petrochemicals(such as,methanol,ethylene and ethylene oxide)produced at the same or nearby complex in order to obtain value-added products while contributing also to CO_(2) fixation simultaneously.Exemplifying worldwide ethylene oxide facilities,it is recognized that they produce about 3 million tons of CO2 annually.Such a CO_(2) resource,which is already separated in pure form as a requirement of the process,should best be converted to a value-added chemical there avoiding current practice of discharging to the atmosphere.The potential utilization of CO_(2),captured at power plants,should also been taken into consideration for sustainability.This CO_(2) source,which is potentially a raw material for the chemical industry,will be available at sufficient quality and at gigantic quantity upon realization of on-going tangible capture projects.Products resulting from carboxylation reactions are obvious conversions.In addition,provided that enough s
文摘Photosynthetic CO2 fixation is the ultimate source of organic carbon on earth and thus is essential for crop production and carbon sequestration, Ribulose-1,5-bis- phosphate carboxylase/oxygenase （Rubisco） catalyzes the first step of photosynthetic CO2 fixation. However, the extreme low carboxylation efficiency of Rubisco makes it the most attractive target for improving pho- tosynthetic efficiency. Extensive studies have focused on re-engineering a more efficient enzyme, but the effort has been impeded by the limited understanding of its structure-function relationships and the lack of an effi- cient selection system towards its activity. To address the unsuccessful molecular engineering of Rubisco, we developed an Escherichia coil-based activity-directed selection system which links the growth of host cell solely to the Rubisco activity therein. A Synechococcus sp. PCC7002 Rubisco mutant with E49V and D82G sub- stitutions in the small subunit was selected from a total of 15,000 mutants by one round of evolution. This mutant showed an 85% increase in specific carboxyla- tion activity and a 45% improvement in catalytic efficiency towards CO2. The small-subunit E49V mutation was speculated to influence holoenzyme catalysis through interaction with the large-subunit Q225. This interaction is conserved among various Rubisco from higher plants and Chlamydomonas reinhardtii. Knowledge of these might provide clues for engineering Rubisco from higher plants, with the potential of increasing the crop yield.
基金the State Key Basic Research and Development Plan of China(2002CB111504)the Project of Turning Cropland to Forest of State Forestry Administration and the Distinguished Young Scientist Fund of the NationalNatural Science Foundation of China (2002002002).
文摘Both the photosynthetic light curves and CO2 curves of Juglans regia L. and Ziziphus jujuba Mill. var. spinosa in three seasons were measured using a LI-6400 portable photosynthesis system. The maximal net photosynthetic rate （Amax）, apparent quantum efficiency（φ）, maximal carboxylation rate （Vcmax） and water use efficiency （WUE） of the two species were calculated based on the curves. The results showed that Amax of J. regia reached its maximum at the late-season, while the highest values of Amax of Z. jujuba occurred at the mid-season. The Amax of J. regia was more affected by relative humidity （RH） of the atmosphere, while that of Z. jujuba was more affected by the air temperature. Light saturation point （LSP） and Light compensation point （LCP） of J. regia had a higher correlation with RH of the atmosphere, those of Z. jujuba, however, had a higher correlation with air temperature. Vcmax of both J. regia and Z. jujuba had negative correlation with RH of the atmosphere. WUE of J. regia would decrease with the rise of the air temperature while that of Z. jujuba increased. Thus it could be seen that RH, temperature and soil moisture had main effect on photosynthesis and WUE of J. regia and Z. jujuba. Incorporating data on the physiological differences among tree species into forest carbon models will greatly improve our ability to predict alterations to the forest carbon budgets under various environmental scenarios such as global climate change, or with differing species composition.
文摘Photosynthetic rate (Pn) and the partitioning of noncyclic photosynthetic electron transport to photorespiration (Jo) in seedlings of four subtropical woody plants growing at three light intensities were studied in the summer time by measurements of chlorophyll fluorescence and CO2 exchange. Except Schima superba, an upper canopy tree species, the tree species Castanopsis fissa and two understory shrubs Psychotria rubra, Ardisia quinquegona had the highest Pn at 36% of sunlight intensity. The total photosynthetic electron transport rate (JF) and the ratio of Jo/JF were elevated in leaves under full sunlight. Jo/JF ratio reached 0.5-0.6 and coincided with the increasing of oxygenation rate of Rubisco (Vo), the activity of glycolate oxidase and photorespiration rate at full sunlight. It is suggested that an increasing partitioning proportion of photosynthetic electron transport to photorespiration might be one of the protective regulation mechanisms in forest plant under strong summer light and high temperature conditions.
基金the Russian Foundation for Basic Research(RFBR grant12-03-31537)
文摘Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under mild reaction conditions （8 bar CO2, 25 ~C）. Styrene and propylene carbonates were formed with high yields （95% and 82%, respectively）. Catalytic performance of Cr-MIL-101 was compared with other MOFs： Fe-MIL-101, Zn-MOF-5 and HKUST-1, The catalytic properties of different quaternary ammonium bromides, Cr-MIL-101 as well as PW12/Cr-MIL-101 composite material have been assessed in oxidative carboxylation of styrene in the presence of both tert-butyl hydroperoxide and H202 as oxidants at 8-100bar CO2 and 25-80 ~C with selectivity to styrene carbonate up to 44% at 57% substrate conversion.
基金We thank the National Natural Science Foundation of China （Nos. 21602052 and 21702151） for financial support.
文摘Carbon dioxide is a ubiquitous and inexpensive one-carbon source for chemical synthesis, and the efficient incorporation of CO2 into organic molecules is of widespread research interest both for economic and ecological reasons. The methodologies to employ carbon dioxide as a single-carbon unit to construct molecules relevant for agrochemical and pharmaceutical research include many elegant approaches, including asymmetric transformations. Even though remarkable achievements have been made in the field of light-driven catalysis, especially photoredox catalysis, homogeneous light-driven catalytic carboxylation by employing CO2 as the key reagent has only become a subject of increasing attention in recent years. Therefore, this concise review will discuss the latest advances in this research area.
基金The National Natural Science Foundation of China (No. 20471030, 30570323) the Foundation of State Planning Committee (No.GFZ040628, BG2005040)
文摘Effects of cerium （Ce^3＋） on photosynthetic characteristics were investigated by hydroponics under laboratory conditions when soybean seedlings were exposed to two levels of supplementary UV-B radiation. UV-B radiation badly inhibited the photosynthesis in soybean seedling, leading to a reduction in net photosynthetic rate （Pn）, Hill reaction activity, light saturated photosynthetic rate （Ps） and apparent quanta yield （AQY）, as well as the CO2 and light saturated photosynthetic rate （Pro） and carboxulation efficiency （CE）. On the contrary, Ce obviously promoted the photosynthesis of plants by increasing Hill reaction activity, accelerating electron transport and photophosphorylation, and enhancing carboxylation efficiency. For Ce＋UV-B treatments, the values of photosynthetic parameters were still lower than those of the control, but obviously higher than those of UV-B treatment. The results indicated that Ce alleviated the inhibition of UV-B radiation on the photosynthesis in soybean seedling to a certain extent. In correlating of Pn with Hill activity, AQY and CE, we found that the changes of photosynthetic rate were mainly influenced by the regulating effect of Ce on Hill activity and AQY at low level （0.15 W/m^2） of UV-B radiation, but were dominated by the regulating effect of Ce on CE at high level （0.45 W/m^2）. Thus, Ce could regulate many aspects in photosynthesis of soybean seedling under UV-B stress. The regulating mechanism was close related with the dosage of UV-B radiation.
