Catalytic performance of Cu/ZnO/Al2O3/ZrO2 for slurry methanol synthesis from CO2 hydrogenation: effect of Cu/Zn molar ratio

Catalytic hydrogenation of carbon dioxide (CO2) to methanol is an attractive way to recycle and utilize CO2. A series of Cu/ZnO/Al2O3/ZrO2 catalysts (CZAZ) containing different molar ratios of Cu/Zn were prepared by the co-precipitation method. The catalysts were characterized by temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive x-ray analysis (FESEM-EDX) and X-ray diffraction (XRD). Higher surface area, SABET values (42.6-59.9 m2/g) were recorded at low (1) and high (5) Cu/Zn ratios with the minimum value of 35.71 m2/g was found for a Cu/Zn of 3. The reducibility of the metal oxides formed after calcination of catalyst samples was also affected due to change in metal-support interaction. At a reaction temperature of 443 K, total gas pressure of 3.0 MPa and 0.1 g/mL of the CZAZ catalyst, the selectivity to methanol decreased as the Cu/Zn molar ratio increased, and the maximum selectivity of 93.9 was achieved at Cu/Zn molar ratio of 0.33. With a reaction time of 3h, the best performing catalyst was CZAZ75 with Cu/Zn molar ratio of 5 giving methanol yield of 6.4%

Separation of hydridocarbonyltris(triphenylphosphine) rhodium (I)catalyst using solvent resistant nanofiltration membrane

An investigation was conducted into the nanofiltration of rhodium tris(triphenyl-phosphine) [HRh(CO)(PPh3)3] catalyst used in the hydroformylation of olefins. The large size of the catalyst (>400 Da) – relative to other components of the reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (STARMEMTM 122 and STARMEMTM 240) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. The morphology of the membrane was studied by field emission scanning electron microscopy (FESEM). The solvent flux and membrane rejection of HRh(CO)(PPh3)3 was then determined for the catalyst-solvent-membrane combination in a dead-end pressure cell. Good HRh(CO)(PPh3)3 rejection (>0.93) coupled with good solvent fluxes (>72 L/m2h1 at 2.0 MPa) were obtained in one of the systems tested. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting the solvent flux

Comparative assessment of various extraction approaches for the isolation of essential oil from polygonum minus using ionic liquids

The recent trend of green consumerism in the modern society has triggered the use of plant-derived chemicals in the food, cosmetics, and fragrance industries. Ionic liquids emerged as an effective solvent for extraction of bioactive compounds from numerous plant resources. The objective of this research was to study the ionic liquid-assisted extraction of essential oil from polygonum minus and to compare the impact of various processing methods such as; microwave, ultrasonic, reflux and mechanical stirring on the yield of essential oil. Ionic liquids with various anions (NTf2, Cl, and Ac) and cations (AMIM, BMIM, and HMIM) were investigated. The performance of these ionic liquids was also compared with the organic solvent such as toluene, pentane, and hexane. The results indicated the cationic and anionic components exhibit remarkable impact on the extraction efficiency of the respective ionic liquids. In addition different processing parameter including extraction time, concentration and solid-liquid ratio were also optimized for all processing techniques employed. The use of Clevenger apparatus in combination with the ionic liquids based various processing techniques was also explored. The combination of Clevenger apparatus with ionic liquid based microwave-assisted extraction (ILMAE) technique showed the highest extraction efficiency of essential oil under the optimized condition of 21 min and 60 °C using [AMIM] Ac. We believe the present work would open for a new pathway for ILs based green extraction of a natural product from renewable resources. Keywords: Microwave, Ultrasonic, Ionic liquids, Clevenger apparatus, Essential oi

Fixed-Bed Adsorption of Phenol onto Microporous Activated Carbon Set from Rice Husk Using Chemical Activation

In the course of this research, the potential of activated carbon from rice husk was examined as being a phenol removal medium from an aqueous solution in a fixed-bed adsorption column. The activated carbon was characterized through FESEM (Field-Emission Scanning Electron Microscopy) and BET (Brunauer–Emmett–Teller) surface area. According to the FESEM micrograph and BET surface area, RHAC (rice husk activated carbon) had a porous structure with a large surface area of 587 m2·g−1 and mean diameter of pores of 2.06 nm. The concentration effects on the influent phenol (100–2000 mg·L−1), rate of flow (5–10 mL·min−1), and bed depth (8.5–15.3 cm) were examined. It was found that the capacity of bed adsorption increased according to the increase in the influent concentration and bed depth. However, the capacity of bed adsorption decreased according to the increase in the feed flow rate. The regeneration of activated carbon column using 0.1 M sodium hydroxide was found to be effective with a 75% regeneration efficiency after three regeneration cycles. Data on adsorption were observed to be in line with many well-established models (i.e., Yoon–Nelson and Adams–Bohart, as well as bed depth service time models)

Fixed-Bed Adsorption of Phenol onto Microporous Activated Carbon Set from Rice Husk Using Chemical Activation

In the course of this research, the potential of activated carbon from rice husk was examined as being a phenol removal medium from an aqueous solution in a fixed-bed adsorption column. The activated carbon was characterized through FESEM (Field-Emission Scanning Electron Microscopy) and BET (Brunauer–Emmett–Teller) surface area. According to the FESEM micrograph and BET surface area, RHAC (rice husk activated carbon) had a porous structure with a large surface area of 587 m2·g−1 and mean diameter of pores of 2.06 nm. The concentration effects on the influent phenol (100–2000 mg·L−1), rate of flow (5–10 mL·min−1), and bed depth (8.5–15.3 cm) were examined. It was found that the capacity of bed adsorption increased according to the increase in the influent concentration and bed depth. However, the capacity of bed adsorption decreased according to the increase in the feed flow rate. The regeneration of activated carbon column using 0.1 M sodium hydroxide was found to be effective with a 75% regeneration efficiency after three regeneration cycles. Data on adsorption were observed to be in line with many well-established models (i.e., Yoon–Nelson and Adams–Bohart, as well as bed depth service time models)

Carbon nanofibers based copper/zirconia catalysts for carbon dioxide hydrogenation to methanol: Effect of copper concentration

A series of novel bimetallic copper/zirconia carbon nanofibers supported catalysts with different Cu contents (5–25 wt%) were synthesized via deposition precipitation method. The physicochemical characterization of the calcined catalysts was carried out by X-ray diffraction, inductively coupled plasma optical emission spectroscopy, N2 adsorption–desorption, N2O chemisorption, temperature programmed reduction, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy and temperature programmed CO2 desorption. Structure-reactivity correlation for catalytic hydrogenation of CO2 to methanol was discussed in details. Reaction studies revealed 15 wt% as optimum Cu concentration for CO2 conversion to methanol with CO2/H2 feed volume ratio of 1:3. Cu surface area was found to play a vital role in methanol synthesis rate. CO2 conversion was observed to be directly proportional to the number of total basic sites. A comparative study of this novel catalyst with the recently reported data revealed the better CO2 conversion at relatively low reaction temperature