Hydrogenation of CO2 into methanol is one of the most economical process to reduce CO2 concentration in the atmosphere. Since methanol is an industrial commodity used in chemical products as well as transportation fuel, this process has gained considerable interest, which enables the effective utilization of CO2. Nevertheless, the efficiency of direct CO2 hydrogenation to produce methanol is strongly reliant on the activity of the catalyst. In this regard, the present work highlights the synthesis of methanol, catalytic evaluation and characterization of catalysts Cu/ZnO supported on Al2O3 and SBA-15 pellets with the addition of group IV, V and VII metal oxides mixture as promoters. The catalysts were systematically prepared via impregnation technique with fixed Cu:Zn and promoter ratio from group VII:V:IV. The synthesized catalysts were characterized by H2-temperature-programmed reduction (H2-TPR), field emission scanning electron microscopy (FESEM), X-ray fluorescence (XRF), N2 adsorption-desorption and N2O pulse chemisorption method. The crushing strength of the pellets were also tested. Catalytic performances were evaluated for methanol synthesis from CO2 hydrogenation in a tubular, stainless steel fixed-bed reactor at 250 °C, 2 MPa, gas hourly space velocity (GHSV) 4000 ml/g.h and H2/CO2 ratio of 3:1. The tri-promoted Cu/ZnO supported on Al2O3 pellet resulted in CO2 conversion of 13.3 % compared to 11.61 % from that of SBA-15-supported catalyst. However, the catalyst supported on SBA-15 pellet exhibited 54.59% methanol selectivity, whereas Al2O3-supported catalyst only resulted in 46.73 % methanol selectivity.

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Acid gas removal mainly CO2 and H2S from natural gas is an essential treatment process in the oil and gas industry to increase the heating value of sales gas, prevent corrosion of pipeline and process equipment’s and avoid crystallization during the liquefaction process (Ahmad et al., 2010). Among the popular acid gas removal technologies, the amine-based acid gas absorption process that relies on chemical absorption of acid gas into aqueous amine solution followed by thermal regeneration is one of the technologies that is widely used in the oil and gas industry for acid gas treatment (Brau et al., 2017; Yu et al., 2012; Tay et al., 2017). For amine-based acid gas removal technology, contactors play an important role to ensure efficient and economical separation processes. Membrane contactor technology is one of the promising alternatives to existing conventional contactors that provides a large surface area per unit volume, independent gas and liquid flow rate and ease of scale-up for the acid gas absorption process. In this study, the feasibility of using membrane contactor technology for CO2 and H2S co-removal at high pressure was investigated. The effect of operating parameters such as gas flow rate, liquid flow rate and amine concentration on CO2 and H2S removal performance using activated MDEA as liquid absorbent was conducted using the design of experiment approach. Results from experimental runs have shown that the H2S target outlet which is ≤50 ppm was achieved at all operating conditions but not for CO2 outlet. The target CO2 outlet which is 6.5 mol% was only achieved at experimental runs where the condition of gas flowrate is the lowest, liquid flowrate is the highest and amine concentration is the lowest. The results achieved have proven that there is a high potential to use membrane contactor technology for co-removal of CO2 and H2S from natural gas.

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Development of new technology in the area of separation process is essential in order to deal with with product quality, environmental issues, energy efficiency, cost reduction and increasing safety. In membrane separation processes, membrane contactor has attained considerable attention due to the wide range of its applications. Since most of chemical separation processes are related to the contact of two different phases (liquid-liquid or gas/vapor-liquid), the operations such as gas absorption and stripping, liquid-liquid extraction, distillation, heterogeneous reactions, emulsification, demulsification, humidification and dehumidification can be conducted through a membrane contactor system (Drioli et al. 2005). Development of membrane contactor for acid gas removal is an emerging technology recently especially to overcme the disadvantages of commercial packed towers and bubble columns. Physical solvents such as DEPG (Selexol™ or Coastal AGR®), NMP or N-Methyl-2-Pyrrolidone (Purisol®), Methanol (Rectisol®), and Propylene Carbonate (Fluor Solvent™) are well known as commercial gas treating solvents, especially for acid gas removal. Physical solvents tend to be favored over chemical solvents when the concentration of acid gases or other impurities is very high (Burr and Lyddon 2008). Among the physical solvents, Selexol shows the highest H2S solubility. However, due to Selexol solvent is less hazard as compared to NMP, this compatibility study was conducted using Selexol as the solvent for H2S removal with various types of polymeric membrane material. The main objective of the study was to test the stability of potential porous membrane material with the selected physical absorbent for H2S removal. From the physical characterization consist of physical abservation, Fe-SEM, FTIR and contact angle that have been conducted on the membranes that have been immersed in the physical absorbent for 1 month, it is found that 3 membrane materials are most stable and compatible with the selected physical absorbent. The 3 shortlisted membrane material are PTFE, PP and PEEK membrane that could be further developed for H2S removal using membrane contactor technology.