carbon dioxide

摘要： After the volcanic eruption of January 17th, 2002, Goma Volcano Observatory (OVG) initiated carbon dioxide (CO2) monitoring in the fractures south of the Nyiragongo volcano and at the northern edge of Lake Kivu. During the period from March 17th, 2017 to June 10th, 2020, twice a week, a GA 5000 gasometer was used for CO2 in the fractures as well as in the mazukus, respectively, as part of a project funded by the Kingdom of the Netherlands through the Lake Kivu Monitoring Program (LKMP) in Rwanda. The level of volcanic activity was determined by the volume of gas emitted by the volcano and measured by a DOAS and the seismicity measured by a network of 15 seismometers managed by the OVG. The results show that the concentration of CO2 in the active fractures from recent Nyiragongo eruptions varies with volcanic activity and the occurrence of a large earthquake in the East African Rift;but in the mazukus there is almost no relationship between CO2 content and volcanic activity. The study also shows that the influence of carbon dioxide in mazukus on the carbon dioxide into the Lake Kivu waters remains a major research question. The purpose of this study is to establish the relationship between the existing Carbon Dioxide (mazukus) in the Northern watershed and that of the deep waters of Lake Kivu.

摘要： The efficient hydrogenation of CO_(2)-derived ethylene carbonate(EC)to yield methanol(MeOH)and ethylene glycol(EG)is a key process for indirect conversion of CO_(2)to MeOH.However,a high H_(2)/EC molar ratio during the hydrogenation process(usually as 180-300)is generally required to achieve good catalytic performance,resulting in high cost and energy consumption for H_(2)circulation in the promising industrial application.Here,we prepared a series of Ni-modified Cu/SiO_(2)catalysts and explored the effects of synthesis methods and Ni contents on catalytic performance under different H_(2)/EC molar ratios.The Cu/SiO_(2)catalyst with 0.2%(mass)Ni loading prepared by co-ammonia evaporation method exhibited above 99%conversion of EC,91%and 98%selectivity to MeOH and EG respectively at H_(2)/EC ratio of 60.And no significant deactivation was observed within 140 h at a lower H_(2)/EC of 40.It is demonstrated that a few of Ni addition could not only promote Cu dispersion and increase surface Cu^(+) species due to the strong interaction between Cu and Ni species,but also form uniformly-dispersed CuNi alloy species and thus enhance the adsorption and dissociation of H_(2).But the excess Ni species would aggregate and segregate to cover partial surface of Cu nanoparticles,leading to a significantly drop of catalytic performance in EC hydrogenation.These insights may provide guidance for further design of catalysts for the ester hydrogenation reactions.

摘要： The cycloaddition between CO_(2)and epoxides to produce cyclic carbonate is an attractive and efficiency pathway for the utilization of CO_(2)as C1 source.The development of catalyst to mediate cycloaddition between CO_(2)and epoxides at low temperature and pressure is still a challenge.Herein,a series of polypyrazoles with glass transition temperature(T_(g))in the range of 42.3-52.5°C were synthesized and served as catalyst to mediate the cycloaddition of CO_(2)and epoxides by the assistant of tetrabutylammonium bromide.The catalytic behaviors of polypyrazole on the model cycloaddition of CO_(2)to epichlorohydrin,including the reaction parameters optimization and versatility were investigated in detail,and excellent yield(99.9%)and selectivity(99%)were obtained under the optimized reaction conditions of70°C and 1.0 MPa for 6.0 h.Noteworthily,the polypyrazole acts as homogeneous catalyst during reaction(higher than T_(g)).And under room temperature,polypyrazoles can be easily separated and recovered,which is a promising feature of a heterogeneous catalyst.Furthermore,the reaction mechanism was proposed.The DFT calculation suggested that the formation of hydrogen bond between pyrazole and epoxide greatly reduced the energy barrier,which play an important role in promoting CO_(2)cycloaddition.

摘要： Understanding CO_(2) diffusion behavior in functional nanoporous materials is beneficial for improving the CO_(2) adsorption,separation,and conversion performances.However,it is a great challenge for studying the diffusion process in experiments.Herein,CO_(2) diffusion in 962 metal–organic frameworks(MOFs)with open Cu sites was systematically investigated by theoretical methods in the combination of molecular dynamic simulations and density functional theory(DFT)calculations.A specific force field was derived from DFT-D2 method combined with Grimme’s dispersion-corrected(D2)density functional to well describe the interaction energies between Cu and CO_(2).It is observed that the suitable topology is conductive to CO_(2) diffusion,and 2D-MOFs are more flexible in tuning and balancing the CO_(2) adsorption and diffusion behaviors than 3D-MOFs.In addition,analysis of diffusive trajectories and the residence times on different positions indicate that CO_(2) diffusion is mainly along with the frameworks in these MOFs,jumping from one strong adsorption site to another.It is also influenced by the electrostatic interaction of the frameworks.Therefore,the obtained information may provide useful guidance for the rational design and synthesis of MOFs with enhanced CO_(2) diffusion performance for specific applications.

摘要： Objective: High-frequency ventilation (HFV) is an effective means to achieve gas exchange in neonates. Adequate carbon dioxide (pCO2) levels are best achieved immediately after starting HFV, avoiding either hypercapnia or hypocapnia. We aimed to determine the initial pCO2 levels after starting HFV, and the time taken to obtain the initial blood gas. Methods: We conducted an observational retrospective study on neonates that required their first episode of HFV. Data included the first blood gas result after starting HFV and when the gas was taken after starting HFV. Results: This study included 112 neonates with a median birth weight of 938 (IQR: 692 - 1549) grams and gestational age of 27.2 (24.6 - 30.7) weeks. The first pCO2 after starting HFV (mean (SD)) was 53.7 (22) mmHg. Of 112, 15 (13.4%) showed initial hypocapnia (pCO2 35 mmHg), and 17 (15.2%) showed hypercapnia (pCO2 > 65 mmHg)—a total of 28.6% unacceptable pCO2 levels. Of 112, the first blood gas was obtained within 30 minutes in 47 (42%) and within one hour in 85 (76%), with a significant delay of two or more hours in eight (7.1%). Conclusion: Many neonates had unacceptable pCO2 levels upon starting first-time HFV. There were significant delays in obtaining the initial gas.

摘要： BACKGROUND Laparoscopic hepatectomy has recently become popular because it results in less bleeding than open hepatectomy.However,CO_(2)embolism occurs more frequently.Most CO_(2)embolisms during laparoscopic surgery are self-resolving and non-symptomatic;however,severe CO_(2)embolism may cause hypotension,cyanosis,arrhythmia,and cardiovascular collapse.In particular,paradoxical CO_(2)embolisms are highly likely to cause neurological deficits.We report a case of paradoxical CO_(2)embolism found on transesophageal echocardiography(TEE)during laparoscopic hepatectomy,although the patient had no intracardiac shunt.CASE SUMMARY A 71-year-old man was admitted for laparoscopic left hemihepatectomy.During left hepatic vein ligation,the inferior vena cava was accidentally torn.We observed a sudden drop in oxygen saturation to 85%,decrease in systolic blood pressure(SBP)below 90 mm Hg,and reduction in end-tidal CO_(2)to 24 mm Hg.A“mill-wheel”murmur was auscultated over the precordium.The fraction of inspired oxygen was increased to 100%with 5 cm H2O of positive end-expiratory pressure(PEEP)and hyperventilation was maintained.Norepinephrine infusion was increased to maintain SBP above 90 mm Hg.A TEE probe was inserted,revealing gas bubbles in the right side of the heart,left atrium,left ventricle,and ascending aorta.The surgeon reduced the pneumoperitoneum pressure from 17 to 14 mm Hg and repaired the damaged vessel laparoscopically.Thereafter,the patient’s hemodynamic status stabilized.The patient was transferred to the intensive care unit,recovering well without complications.CONCLUSION TEE monitoring is important to quickly determine the presence and extent of embolism in patients undergoing laparoscopic hepatectomy.

摘要： Injecting CO_(2)into the underground for oil displacement and shortage is an important technique for carbon capture,utilization and storage(CCUS).One of the main problems during the CO_(2)injection is the channeling plugging.Finding an effective method for the gas channeling plugging is a critical issue in the CO_(2)EOR process.In this work,an acid-resistance microgel named dispersed particle gel(DPG)was characterized and its stability was tested in the CO_(2)environment.The microgel size selection strategies for the homogeneous and heterogeneous reservoirs were respectively investigated using the single core flooding and three parallel core flooding experiments.Moreover,the comparison of microgel alternate CO_(2)(MAC)injection and water alternate CO_(2)(WAC)injection in the dual core flooding experiments were presented for the investigation of the role of microgel on the conformance control in CO_(2)flooding process.The results have shown that the microgel featured with ANH and CAN groups can keep its morphology after aging 7 days in the CO_(2)environment.Where,the small microgel with unobstructed migration and large microgel with good plugging efficiency for the high permeability zone were respectively featured with the higher recovery factor in homogeneous and heterogeneous conditions,which indicate they are preferred used for the oil displacement and conformance control.Compared to WAC injection,MAC injection had a higher incremental recovery factor of 12.4%.It suggests the acid-resistance microgel would be a good candidate for the conformance control during CO_(2)flooding process.

摘要： The persistent rise in concentrations of greenhouse gases (GHGs) in the earth’s atmosphere is responsible for global warming and climate change. Besides the known source of GHGs emissions like energy, industry, and agriculture, intrinsic emissions from natural inland water bodies like wetland, rivers, reservoirs, estuaries, etc. have also been identified as other hotspots of GHGs emission and gaining the attention of the scientific communities in recent times. Inland fisheries in India are threatened by climate changes such as a change in temperature, precipitation, droughts, storm, sea-level rise, saltwater intrusion, floods that affect mostly the production, productivity and ultimately affect the fishers’ livelihood. There are, however, different mitigation and adaptation strategies to cope with the effects of climate change. Carbon sequestration and other related management interventions are one of the options available minimizing GHGs emissions from inland open waters, particularly the wetlands and coastal mangroves which are well known worldwide for their significant role in the storage of carbon. Assessment of C efflux from exposed sediments in dry streams, reservoirs, lakes, rivers, and ponds into the atmosphere can be considered imperative for a better understanding of their role as a C-sink or as a C-source to the atmosphere.

摘要： Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride catalysts,theγ-Mo_(2)N exhibits superior activity to target product CO,which is 4.6 and 76 times higher than the other two counterparts ofβ-W_(2)N andδ-NbN at 600°C,respectively.Additionally,γ-Mo_(2)N exhibits excellent stability on both cyclic heating-cooling and high space velocity steady state operation.The deactivation degree of cyclic heating-cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%.In-situ XRD and kinetic studies suggest that theγ-Mo_(2)N itself is able to activate both of the reactants CO_(2)and H_(2).Below 400°C,the reaction mainly occurs at the surface ofγ-Mo_(2)N catalyst.CO_(2)and H_(2)competitively adsorbe on the surface of catalyst and CO_(2)is the relatively stronger surface adsorbate.At a higher temperature,the interstitial vacancies of theγ-Mo_(2)N can be reversibly filled with the oxygen from CO_(2)dissociation.Both of the surface and bulk phase sites ofγ-Mo_(2)N participate in the high temperature CO_(2)hydrogenation pathway.

摘要： Dry reforming of methane(DRM) involves the conversion of carbon dioxide(CO_(2)) and methane(CH_(4)) into syngas(a mixture of hydrogen, H_(2), and carbon monoxide, CO), which can then be used to produce a wide range of products by means of Fischer–Tropsch synthesis. DRM has gained much attention as a means of mitigating damage from anthropogenic greenhouse gas(GHGs) emissions to the environment and instead utilizing these gases as precursors for value-added chemicals or to synthesize sustainable fuels and chemicals. Carbon deposition or coke formation, a primary cause of catalyst deactivation, has proven to be a major challenge in the development of DRM catalysts. The use of nickel-and cobalt-based catalysts has been extensively explored for DRM for their high activity and low cost but suffer from poor stability due to coke formation that has hindered their commercialization. Numerous articles have reviewed the various aspects of catalyst deactivation and strategies for mitigation, but few has focused on the benefit of bimetallic catalysts for mitigating coke formation. Bimetallic catalysts, often improve the catalytic stability over their monometallic counterparts due to synergistic effects resulting from two metal-tometal interactions. This review will cover DRM literature for various bimetallic catalyst systems, including the effect of supports and promoters, on the mitigation of carbonaceous deactivation.

摘要： Paper developed fluid sensitive experiments basing on the cores of carbonate reservoir with high content H2S and CO2 gas in Kazakhstan Zhanazhol, middle and northeast parts of Sichuan Basin of China. Results show there is certain level fluids sensitivity in cores, and alkali sensitivity is the most serious. Petrography analysis that dolomite, calcite, microcrystalline quartz, gypsum, illite, CaS, asphalt are common in the study area carbonate reservoir. Alkali working fluids intrude into reservoir, change reservoir original acidic environment. Alkali working fluids consumption of acidic and destruction rock interface, resulting more sensitive mineral exposure and physical and chemical changes occur, which cause more serious formation damage. Alkali fluids intrusive, cause sulfur deposition. Based on such formation damage mechanism, the article says to vigorously develop technology of temporary shielding.

摘要： Paper developed fluid sensitive experiments basing on the cores of carbonate reservoir with high content H2S and CO2 gas in Kazakhstan Zhanazhol, middle and northeast parts of Sichuan Basin of China. Results show there is certain level fluids sensitivity in cores, and alkali sensitivity is the most serious. Petrography analysis that dolomite, calcite, microcrystalline quartz, gypsum, illite, CaS, asphalt are common in the study area carbonate reservoir. Alkali working fluids intrude into reservoir, change reservoir original acidic environment. Alkali working fluids consumption of acidic and destruction rock interface, resulting more sensitive mineral exposure and physical and chemical changes occur, which cause more serious formation damage. Alkali fluids intrusive, cause sulfur deposition. Based on such formation damage mechanism, the article says to vigorously develop technology of temporary shielding.

摘要： Paper developed fluid sensitive experiments basing on the cores of carbonate reservoir with high content H2S and CO2 gas in Kazakhstan Zhanazhol, middle and northeast parts of Sichuan Basin of China. Results show there is certain level fluids sensitivity in cores, and alkali sensitivity is the most serious. Petrography analysis that dolomite, calcite, microcrystalline quartz, gypsum, illite, CaS, asphalt are common in the study area carbonate reservoir. Alkali working fluids intrude into reservoir, change reservoir original acidic environment. Alkali working fluids consumption of acidic and destruction rock interface, resulting more sensitive mineral exposure and physical and chemical changes occur, which cause more serious formation damage. Alkali fluids intrusive, cause sulfur deposition. Based on such formation damage mechanism, the article says to vigorously develop technology of temporary shielding.

摘要： Paper developed fluid sensitive experiments basing on the cores of carbonate reservoir with high content H2S and CO2 gas in Kazakhstan Zhanazhol, middle and northeast parts of Sichuan Basin of China. Results show there is certain level fluids sensitivity in cores, and alkali sensitivity is the most serious. Petrography analysis that dolomite, calcite, microcrystalline quartz, gypsum, illite, CaS, asphalt are common in the study area carbonate reservoir. Alkali working fluids intrude into reservoir, change reservoir original acidic environment. Alkali working fluids consumption of acidic and destruction rock interface, resulting more sensitive mineral exposure and physical and chemical changes occur, which cause more serious formation damage. Alkali fluids intrusive, cause sulfur deposition. Based on such formation damage mechanism, the article says to vigorously develop technology of temporary shielding.

摘要： Paper developed fluid sensitive experiments basing on the cores of carbonate reservoir with high content H2S and CO2 gas in Kazakhstan Zhanazhol, middle and northeast parts of Sichuan Basin of China. Results show there is certain level fluids sensitivity in cores, and alkali sensitivity is the most serious. Petrography analysis that dolomite, calcite, microcrystalline quartz, gypsum, illite, CaS, asphalt are common in the study area carbonate reservoir. Alkali working fluids intrude into reservoir, change reservoir original acidic environment. Alkali working fluids consumption of acidic and destruction rock interface, resulting more sensitive mineral exposure and physical and chemical changes occur, which cause more serious formation damage. Alkali fluids intrusive, cause sulfur deposition. Based on such formation damage mechanism, the article says to vigorously develop technology of temporary shielding.

摘要： Paper developed fluid sensitive experiments basing on the cores of carbonate reservoir with high content H2S and CO2 gas in Kazakhstan Zhanazhol, middle and northeast parts of Sichuan Basin of China. Results show there is certain level fluids sensitivity in cores, and alkali sensitivity is the most serious. Petrography analysis that dolomite, calcite, microcrystalline quartz, gypsum, illite, CaS, asphalt are common in the study area carbonate reservoir. Alkali working fluids intrude into reservoir, change reservoir original acidic environment. Alkali working fluids consumption of acidic and destruction rock interface, resulting more sensitive mineral exposure and physical and chemical changes occur, which cause more serious formation damage. Alkali fluids intrusive, cause sulfur deposition. Based on such formation damage mechanism, the article says to vigorously develop technology of temporary shielding.