THE ROLES OF CARBON DIOXIDE IN METHANOL SYNTHESIS

The roles played by carbon dioxide in the chemistry of methanol synthesis over CuO/ZnO/A1₂O₃ catalysts have been experimentally investigated. It was concluded based on reaction rate measurements and thermodynamic considerations, that the two reactions that best describe the chemical system of methanol synthesis are the CO₂-hydrogenation and water-gas shift reactions. It was also found experimentally that the presence of CO₂ is vital for maintaining the catalytic activity. The significance of the study is enhanced by the fact that this was the first such investigation of the global chemistry of methanol synthesis to be based on the novel liquid phase process. It was also observed that the rates of methanol synthesis attained a maximum when the concentration of carbon dioxide in the reactor feed was controlled at a certain optimal value. The optimal CO₂ content was found to be a function of the operating temperature and syngas composition. The experimental data are especially important because the apparatus and the operating conditions have been well-defined and carefully chosen to closely simulate industrial reactors.     

STUDY OF CHEMICAL EQUILIBRIA IN METHANOL SYNTHESIS I. Expertmental Measurement of Chemical Equilibrium Composition and Constant Kp

Abstract

The chemical equilibrium compositions and equilibrium constants of methanol synthesis reactions, starting from carbon monoxide, carbon dioxide and hydrogen, were studied experimentally at P=4.0-8. 6MP_a and t = 220～260°C. It was found that lower temperatures and higher pressures are favourable to chemical equilibria In the interested range of the synthesis reactions using low-pressure process, but the influence of temperature on K_p Is much larger than that of pressure.     

THE ROLE OF WATER IN METHANOL SYNTHESIS

Abstract

This work focuses on the influence of water in determining the rate of methanol synthesis over CuO/ZnO/Al₂O₃ catalysts. The experimental investigations were conducted in a 1-L slurry reactor based on the novel liquid phase methanol synthesis process. The liquid medium used was a blend of paraffinic and naphthenic mineral oils with a mean molecular mass of 250. It was found that the methanol rates attained a maximum at an optimal water content which was dependent on the reaction temperature. The catalytic activity was found to decline with time at lower temperatures in the presence of a relatively large excess of water. The influence of water was also found to be firmly linked to the corresponding carbon dioxide content in the reactor feed. The experimental data bear additional significance because this was the first such study to be performed on the liquid phase process. Emphasis was therefore placed on the use of a CO-rich syngas in order to simulate anticipated process conditions.     

POST-REDUCTION TREATMENT OF LIQUID PHASE METHANOL SYNTHESIS CATALYST USING CARBON DIOXIDE

ABSTRACT

This work focuses on the investigation of the catalyst post-treatment in the liquid phase methanol synthesis process. The novel post-treatment process, using carbon dioxide, has been developed and experimentally proven to be effective not only in maintaining the initial catalytic activity over a long period of usage but also in improving the mechanical and chemical strength of the catalyst. It was also found that the role of ZnO in the catalytic reaction, if any, can be nicely replaced by ZnCO₃.     

A Simulation Study of Carbon Dioxide Sequestration in a Depleted Oil Reservoir

Abstract

Oil fields offer significant potential for storing carbon dioxide (CO₂) and will most likely be the first large-scale geological targets for sequestration because the infrastructure, experience, and permitting procedures already exist. In addition, almost 40 years' experience in enhanced oil recovery (EOR) allows utilization of carbon capture and storage (CCS) and CO₂ sequestration techniques in such a way as to improve recovery of petroleum fields and reduce the environmental issue of fossil fuel combustion gas products, particularly carbon dioxide. Carbon dioxide is one of the main greenhouse gases that causes global warming.

As a response to global warming, geologic sequestration of CO₂ in oil and gas reservoirs is one possibility to reduce the amount of CO₂ released to the atmosphere. This simulation study presents a synthetic geologic model that is used to sequestrate carbon dioxide beside an EOR immiscible displacement process.     

STUDY OF CHEMICAL EQUILIBRIA IN METHANOL SYNTHESIS I. Expertmental Measurement of Chemical Equilibrium Composition and Constant Kp

The chemical equilibrium compositions and equilibrium constants of methanol synthesis reactions, starting from carbon monoxide, carbon dioxide and hydrogen, were studied experimentally at P=4.0-8. 6MP_a and t = 220∼260°C. It was found that lower temperatures and higher pressures are favourable to chemical equilibria In the interested range of the synthesis reactions using low-pressure process, but the influence of temperature on K_p Is much larger than that of pressure.     

The Equilibrium Data and Thermodynamic Modeling of Hydrate Formation for CO2 and Mixtures of CO2 and CH4 in the Presence of Methanol

Equilibrium data for the novel formation of hydrates of carbon dioxide and mixtures of carbon dioxide and methane in 20 wt% aqueous methanol solution were measured by the constant-volume method. For CO₂, these data were taken at the temperature and pressure ranges of 264.7–270.7 K and 1,470–3,160 kPa, respectively. For mixtures of carbon dioxide and methane, these data were taken at the temperature and pressure ranges of 262.9–273.7 K and 1,370–5,100 kPa, respectively. The data obtained for CO₂ in 20 wt% aqueous methanol solution were in disagreement with previously published data, but there was good agreement between our data and the predictions of thermodynamic models. The Peng-Robinson equation of state (PR EOS) coupled with the Wong-Sandler (WS) mixing rule was used to obtain the fugacities of the components in the gas and aqueous liquid phases. The PR EOS was then coupled with van der Waals-Platteeuw (vdW-P) hydrate model and applied to predict hydrate-formation conditions in the system containing methanol. The model predictions demonstrated good agreement with the experimental data.     

Methanol synthesis revisited: reaction mechanisms in CO/CO2 hydrogenation over Cu/ZnO and DFT analysis

One of the very long-standing controversies in CO/CO₂ hydrogenation chemistry has been the following: What is the principal source of C in the methanol product, CO or CO₂? In other words, do CO hydrogenation and CO₂ hydrogenation proceed independently, in parallel, over the industrial Cu/ZnO/Al₂O₃ catalyst? Using state of the art experimental data and our analysis of prior studies and experimental techniques including isotopic labeling studies, including radioactive tracers, FTIR, XPS, and E-TEM, we discuss the experimental findings of the prior art and analyze the experimental and theoretical first-principles calculational data, to come up with a rational and cogent explanation for all controversial areas in methanol synthesis chemistry.     

Formation of carbon dioxide in the Fischer-Tropsch synthesis on nanosized iron catalyst particles

The formation of carbon dioxide in the Fischer-Tropsch synthesis performed in a three-phase system in the presence of a nanosized catalyst was studied. The synthesis temperature was found the main parameter responsible for the yield of CO₂. At a constant conversion of CO, pressure has almost no effect on selectivity for the formation of CO₂, whereas a decrease in the H₂/CO ratio and an increase in the contact time or the concentration of an active component in the reaction zone lead to a decrease in the selectivity.     

SCREENING CRITERIA FOR CO2 STORAGE IN OIL RESERVOIRS

ABSTRACT

Oil fields are likely to the first category of geologic formation where carbon dioxide (CO₂) is injected for sequestration on a large scale, if geologic sequestration proves feasible. About 1.4 BCF per day (69 300 tonnes/day) of CO₂ are currently injected for oil recovery in the U.S. Replacing this naturally occurring CO₂ with anthropogenic CO₂ would have a minor, but measurable, effect on overall CO₂ emissions. However, CO₂ is injected into only a small fraction of reservoirs and it is estimated that upwards of 80% of oil reservoirs worldwide might be suitable for CO₂ injection based upon oil recovery criteria alone. These facts combined with the generally extensive geologic characterization of oil reservoirs and the maturity of CO₂–oil recovery technology make oil reservoirs attractive first targets as CO₂ sinks. This paper lays the groundwork necessary to evaluate whether an oil reservoir might be suitable for CO₂ storage. As such, a series of criteria for injection into currently producing, depleted, or inactive reservoirs are proposed. Aspects considered include the reservoir depth, storage capacity, water and oil volumes in place, formation thickness, and permeability. Importantly, the effect of oil production on reservoir properties, especially fault movement and induced fractures must be gauged and included in assessments. It is demonstrated that CO₂ density with depth alone is not a sufficient criterion for choosing candidate sites. It is necessary to consider also porosity and the amount of water and oil that are displaceable. The end result is a criteria table for rapid screening of candidate reservoirs.     

CO2利用在有机合成中的研究进展

大气中CO₂含量不断增加对环境和社会的影响是目前全球面临的最重大挑战之一。作为减缓和适应气候变化的行之有效的手段,碳捕获、利用和封存已引起越来越多的关注。其中,CO₂利用,即直接使用CO₂或将其转化为更有价值的产品,已成为减少CO₂排放广泛战略中的一个极其重要的组成部分,这一挑战的实现需要技术和政策变革的支撑。总结和讨论了近20年来国内外利用催化、合成技术,将CO₂转化为高附加值特定化学品(如甲酸、甲醇、聚合物等)的工艺研究进展和存在的相关挑战,并从原子高效率利用和工业角度,提出一些以CO₂为合成原料的具有一定工业应用前景的有机合成方法,如基于CO₂的聚醚醇碳酸酯和聚碳酸酯的合成,并指出实现这一工业应用面临的难点和挑战。     

Economical Evaluation of CO2-EOR Projects in the Middle East

Abstract

Recently, there is a growing interest the in oil industry to utilize carbon dioxide (CO₂) to enhance oil production from mature reservoirs. Conversely, there is a rising global attention to reduce CO₂ emissions from burning fossil fuels due to environmental concerns. Synchronization between these two objectives is promising through CO₂ Capture and Storage (CCS) projects where CO₂ is captured from large emission sources and then storedin safe geological structures. Economical evaluation of CO₂-EOR projects is a crucial measure in order to ensure a project's viability.

In this study, an efficient model was developed to predict the economics of CO₂-EOR projects. The developed model consists of five modules that are linked together to allow for fast prediction of CO₂-EOR economics.

The model was used to predict the economics of a case study where CO₂-EOR application is considered for a Middle Eastern reservoir. Moreover, the case study was subjected to sensitivity analyses to evaluate the effects of several parameters on the various economical components of CO₂-EOR projects.     

MASS TRANSFER CCMPARISON BEIWEEN MECHANICALLY AGITATED SLURRY REACTCR AND LIQUID ENTRAINED REACTOR IN THE METHANOL SYNTHESIS PROCESS

ABSTRACT

The commercial reactor proposed for the liquid phase methanol synthesis process (LPMeCHTM) is a liquid entrained reactor (LER), since it possesses several operational advantages over a mechanically agitated slurry reactor (MASR). This paper discusses in detail the develocment of a correlation for the prediction of the overall gas-liquid mass transfer coefficient (KLiaB) in a LER. The overall mass transfer coefficient experimentally determined for the LER, is compared with the corresponding value obtained for the MASR under nominally identical operating conditions. It was observed that the overall gas-liquid mass transfer coefficient and hence the overall rate of methanol production per unit mass of catalyst, is significantly higher in the LER compared to the MASR at identical operating conditions. In the LER mode, the limitation posed on the system by chemical equilibrium, is alleviated by selective renewal of products thus making the process ideal for the once-through methanol (CIM) This justifies the proposed commercial mode of synthesis of methanol in the liquid entrained reactor.     

Carbon dioxide reforming of alcohols on porous membrane catalyst systems

The features of the carbon dioxide reforming of ethanol and an ethanol-glycerol mixture to synthesis gas in the presence of porous membrane catalyst systems have been studied. It has been shown that the CO₂ reforming of alcohols in open pores of ceramic membranes modified with nanosized active palladiumcontaining components proceeds at a higher rate as compared to that in a conventional fixed-bed flow reactor charged with a catalyst of similar composition.     

The Impact of Pore Pressure on CO2-Methane Displacement

Abstract

The intricate behavior of carbon dioxide at supercritical conditions is considered to influence the ultimate recovery of additional hydrocarbon reserves through the application of CO₂-enhanced gas recovery projects. Mixing in such a system is a diffusion-like process, which definitely depends on the physical properties of the displacing and displaced phases and the heterogeneity of the medium. The authors' aim was to experimentally investigate the consequence of pore pressure on the recovery efficiency and multiphase gas flow in a reservoirs porous medium. The displacement tests were carried out at five different pore pressures ranging from 10.34 to 40.68 MPa, temperature of 433.15 K, and displacement rate of 10 cm/hr. Results determined that improved recovery by approximately 40% can be obtained by applying the highest pore pressure in comparison with the test conducted at low pore pressure.     

Reactive transport modeling for CO2 geological sequestration

One way to reduce carbon dioxide (CO₂) releases to the atmosphere, is to capture it from power plants and then inject it into deep geological formations. Understanding water-gas-mineral reactions is the core of assessing the long term storage and risks in geological sequestration. Because of various limitations of laboratory and field tests, reactive transport modeling has been one important supplementary or independent tool to study the water–gas–mineral reactions at different components of geological sequestration. In this paper, we reviewed the applications of reactive transport modeling to three aspects of CO₂ geological sequestration: the behavior of CO₂ in storage formation, the storage security issues related to caprock integrity or wellbore cement degradation, and the change of the shallow groundwater in response to the potential leakage of CO₂. Key finding are summarized and further research needs are identified. The lack of the detailed mineralogical composition information at the storage formation, caprock and overlying aquifers is currently the first obstacle for quantitative prediction of geochemical evolution. The thermodynamic properties of relevant minerals under high temperature and pressure have to be refined. Reliable reaction rates of minerals dissolution/precipitation at field are still the bottle neck of the calculating the long term mineral trapping of CO₂. Issues related to relatively fast reactions such sorption and ion exchange need special attention when the impact of CO₂ leakage on shallow groundwater was evaluated. The role of organic compounds in water-gas-mineral reactions needs further study.     

CO2捕集技术的研究现状与发展趋势

目的在全球节能减排的大背景以及我国“碳达峰、碳中和”的双碳战略目标指导下,有针对性地研究适用于不同工况的CO₂捕集技术成为极其重要的研究趋势。 方法结合碳捕集领域最新发展动态,针对燃烧过程中CO₂的排放,对比了吸收法、吸附法、深冷分离、膜吸收法、超重力法等技术的优缺点以及应用动态,分析总结了CO₂捕集技术的发展趋势。 结果阐明了几种CO₂燃烧后捕集技术的技术特点。明晰了当前吸收法中吸收剂的选择是核心,反应器与操作条件的优化是重点。对于吸附法,面向大规模工业应用,开发选择性高、吸附容量高、解吸能力强、价格便宜的吸附剂是关键。而对于膜技术,其特点是操作简便、灵活,但提高膜的性能依然是需要持续进行的研究。总体而言,阐明了几种捕集技术的特点、应用潜力和研究方向。 结论尽管当前已经有较多CO₂吸收与分离技术得到广泛的研究与应用,但在具体应用中仍存在诸多问题,针对CO₂吸收与分离的新材料、新溶剂的研究仍是碳捕集领域研究的前沿与热点课题。从碳捕集技术层面出发,今后的发展趋势很可能是两种或两种以上技术串联使用,以满足更多工况条件下的脱碳需求。      

On Estimating the Water Content of CO2 in Equilibrium With Formation Brine

Abstract

Water content of carbon dioxide (CO₂) is an important parameter in engineering applications, such as CO₂ storage in deep saline aquifers and enhanced oil recovery processes. A large number of experimental data have been reported on solubility of CO₂ in brine. However, experimental data on water content of CO₂ in equilibrium with formation brine are not reported in the literature. Water content of natural gas is traditionally calculated by general water content charts; however, these charts are not available for CO₂ in equilibrium with formation brine. Using an accurate fugacity and activity model available in the literature, the authors developed an efficient and simple procedure to estimate the water content of CO₂ in equilibrium with formation brine. To validate the developed procedure, the predicted CO₂-rich phase water content is compared with the reported experimental data in the literature and other predictive models for CO₂-water system. A CO₂ water content chart is presented that can be simply used to predict the water content of CO₂ in equilibrium with formation brine. The procedure presented may be used for generating necessary input data for flow simulation of CO₂ storage in deep saline aquifers.     

Laboratory investigation of carbon dioxide separation from methane using a PES/Pebax 1657 composite membrane

Removal of carbon dioxide from methane is a critical issue in the gas sweetening and treatment units. The aim of this study is to investigate the capability of PES/Pebax composite membrane in order to CO₂ removal from the CH₄. In this regard, permeability values of both carbon dioxide and methane have been measured. The ranges of temperature and pressure used for pure gases experiments were 20–50°C and 2.5–10 bar, respectively. Moreover, influence of CO₂ concentration on the CH₄ permeability and its selectivity was studied. Results indicated that the pressure and temperature have significant influence on permeability and selectivity. In addition, for the gas mixtures, experiments were carried out at 5 bar and 35°C. Results also indicated that at higher CO₂ concentrations the CO₂ permeability increased significantly.     

Enhanced Natural Gas and Condensate Recovery by Carbon Dioxide and Methane Flooding

Abstract

The authors quantitatively investigates the recovery efficiency, pattern behavior, and relative permeability of (a) condensate following supercritical carbon dioxide (CO₂) injection, methane (CH₄) injection, and the injection of their mixtures; and (b) natural gas of various compositions following pure supercritical CO₂ injection. A high-pressure high-temperature experimental laboratory was established to simulate reservoir conditions and to perform relative permeability measurements on sandstone cores. This work is part of an integrated enhanced natural gas and condensate recovery project conducted for a local reservoir in Western Australia. This data will help the operators develop operational and design strategies for their present and future EOR projects.