Tuning adsorption properties of GaxIn2−xO3 catalysts for enhancement of methanol synthesis activity from CO2 hydrogenation at high reaction temperature

Light olefins can be produced from CO2 hydrogenation in a single reactor using a combination of a methanol synthesis catalyst and a methanol-to-olefin (MTO) catalyst. However, commercial methanol synthesis catalysts are active at low temperatures (200–260 °C), while MTO reaction is feasible at higher temperatures (>300 °C). Herein, we report the CO2 hydrogenation to methanol at high temperatures (320–400 °C) over GaxIn2−xO3 catalysts. By tuning the Ga/In ratios, phase, crystallinity, pore structure, morphology, electronic properties as well as adsorptive properties of GaxIn2−xO3 catalysts can be modified. At the lowest temperature (320 °C), the pure In2O3 shows the highest methanol yield. However, the maximum methanol yield declines significantly with increasing reaction temperatures. Incorporation of Ga into the In2O3 crystal lattices at x = 0.4 (Ga0.4In1.6O3) maximizes the methanol yield at higher reaction temperatures of 340–360 °C. This enhancement can be attributed to an increased binding energy of adsorptive molecules with the catalyst surface to promote the hydrogenation of CO2 to methanol. Further increasing Ga content (x > 0.4) leads to greatly strengthen the binding for adsorptive molecules, resulting in a lower methanol yield and the formation of methane. The surface chemisorbed oxygen is found to be a key factor determining the CO yield

A review on advances in green treatment of glycerol waste with a focus on electro-oxidation pathway

Over the past decades, research efforts are being devoted into utilizing the biomass waste as a major source of green energy to maintain the economic, environmental, and social sustainability. Specifically, there is an emerging consensus on the significance of glycerol (an underutilised waste from biodiesel industry) as a cheap, non-toxic, and renewable source for valuable chemicals synthesis. There are numerous methods enacted to convert this glycerol waste to tartronic acid, mesoxalic acid, glyceraldehyde, dihydroxyacetone, oxalic acid and so on. Among these, the green electro-oxidation technique is one of the techniques that possesses potential for industrial application due to advantages such as non-toxicity process, fast response, and lower energy consumption. The current review covers the general understanding on commonly used techniques for alcohol (C1 & C2) conversion, with a specific insight on glycerol (C3) electro-oxidation (GOR). Since catalysts are the backbone of chemical reaction, they are responsible for the overall economy prospect of any processes. To this end, a comprehensive review on catalysts, which include noble metals, non-noble metals, and non-metals anchored over various supports are incorporated in this review. Moreover, a fundamental insight into the development of future electrocatalysts for glycerol oxidation along with products analysis is also presented

Tuning interactions of surface‐adsorbed species over Fe−Co/K−Al2O3 catalyst by different K contents: selective CO2 hydrogenation to light olefins

Selective CO2 hydrogenation to light olefins over Fe−Co/K−Al2O3 catalysts was enhanced by tuning bonding strengths of adsorbed species by varying the content of the K promotor. Increasing the K/Fe atomic ratio from 0 to 0.5 increased the olefins/paraffins (O/P) ratio by 25.4 times, but then slightly raised upon ascending K/Fe to 2.5. The positive effect of K addition is attributed to the strong interaction of H adsorbed with the catalyst surface caused by the electron donor from K to Fe species. Although the Fe−Co/K−Al2O3 catalyst with K/Fe=2.5 reached the highest O/P ratio of 7.6, the maximum yield of light olefins of 16.4 % was achieved by the catalyst promoted with K/Fe of 0.5. This is explained by the considerable reduction of amount of H2 adsorbed on the catalyst surface with K/Fe=2.5

Dengue Virus Ensures Its Fusion in Late Endosomes Using Compartment-Specific Lipids

Many enveloped viruses invade cells via endocytosis and use different environmental factors as triggers for virus-endosome fusion that delivers viral genome into cytosol. Intriguingly, dengue virus (DEN), the most prevalent mosquito-borne virus that infects up to 100 million people each year, fuses only in late endosomes, while activation of DEN protein fusogen glycoprotein E is triggered already at pH characteristic for early endosomes. Are there any cofactors that time DEN fusion to virion entry into late endosomes? Here we show that DEN utilizes bis(monoacylglycero)phosphate, a lipid specific to late endosomes, as a co-factor for its endosomal acidification-dependent fusion machinery. Effective virus fusion to plasma- and intracellular- membranes, as well as to protein-free liposomes, requires the target membrane to contain anionic lipids such as bis(monoacylglycero)phosphate and phosphatidylserine. Anionic lipids act downstream of low-pH-dependent fusion stages and promote the advance from the earliest hemifusion intermediates to the fusion pore opening. To reach anionic lipid-enriched late endosomes, DEN travels through acidified early endosomes, but we found that low pH-dependent loss of fusogenic properties of DEN is relatively slow in the presence of anionic lipid-free target membranes. We propose that anionic lipid-dependence of DEN fusion machinery protects it against premature irreversible restructuring and inactivation and ensures viral fusion in late endosomes, where the virus encounters anionic lipids for the first time during entry. Currently there are neither vaccines nor effective therapies for DEN, and the essential role of the newly identified DEN-bis(monoacylglycero)phosphate interactions in viral genome escape from the endosome suggests a novel target for drug design

Treatment technologies of palm oil mill effluent (POME)and olive mill wastewater (OMW): A brief review

Attributable to the enormous population growth, tonnes of effluents are unavoidably generated throughout the agricultural activities. The inadequate effluents disposal induces perpetual contamination to the sea and river water sources, which has subsequently raised the public environmental concern. For that reason, the handling protocol of agricultural effluents was flagged up as an interest area for research. Despite the environmental hazards, agricultural effluents have the potential to be transformed from wastes into wealth via biological, physicochemical, thermochemical or a combination of processes thereof. The identical characteristics of palm oil mill effluent (POME)and olive mill wastewater (OMW)render the possibility of treating these wastes using the similar treatment method. Generally, biological treatment requires a longer process time compared to physicochemical and thermochemical technologies despite its easy and low-cost operation. Comparatively, physicochemical and thermochemical methods extend their potentiality in converting the agricultural effluents into higher value products more efficiently. This paper reviews the source and characteristics of both POME and OMW. Subsequently, a comparison of the current and alternative treatments for both effluents was done before the future perspectives of both effluents’ treatment are paved based on the well-being of the human, environment, and economic

Ethylene production from ethanol dehydration over mesoporous SBA-15 catalyst derived from palm oil clinker waste

The silica-rich palm oil clinker (POC) from oil palm agroindustry is often dumped in landfill. This work investigated the valorisation of POC into Santa Barbara Amorphous-15 (SBA-15) catalyst, the modulation of its surface acidity, and its application in dehydration of ethanol to ethylene. With commercial SBA-15 [SBA-15(Comm.)] as reference, the successful fabrication of POC-derived SBA-15 [POC-SBA-15(pH = 3, 5, and 7)] were validated by spectroscopic and microscopic characterisation. From the results of temperature-programmed desorption of ammonia, the SBA-15(Comm.) have high strong acidity while POC-SBA-15 exhibit enriched weak-moderate acidity. For ethanol dehydration over SBA-15 at 200–400 °C, the ethanol conversion (XC2H5OH) and ethylene selectivity (SC2H4) rise with temperature. The catalytic activity was ranked as SBA-15(Comm.) 16 mL/g•h, the saturation of finite active sites with adsorbates renders the drastic declination of XC2H5OH and SC2H4. For ethanol dehydration over POC-SBA-15(5), the optimal conditions are temperature of 400 °C, initial ethanol concentration of 50 wt%, and LHSV of 16 mL/g•h. Fresh POC-SBA-15(5) steadily catalyses the optimal process (73.33% XC2H5OH and 84.70% SC2H4) up to 105 h. Meanwhile, regenerated POC-SBA-15(5) achieves a lower catalytic activity (71.95% XC2H5OH and 81.96% SC2H4)

Syngas from catalytic steam reforming of palm oil mill effluent: An optimization study

In this work, the syngas production rate (FSyngas) of LaNiO3-catalysed steam reforming of palm oil mill effluent (POME) was optimized with respect to POME flow rate ( _VPOME), catalyst weight (Wcat), and particle size (dcat). With a net acidity, the synthesized LaNiO3 catalysed POME steam reforming by cracking the bulky compounds and valorising simpler intermediates into syngas. The degradation efficiencies (XP) were also evaluated by assessing wastewater parameters, viz. pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS), and colour intensity (A). After steam reforming at 873 K, the liquid condensate has neutral pH and zero TSS. The parallel trend of FSyngas and XP verified syngas generation from degradation of POME's organics. At higher_V POME (0.05e0.09 mL/min), greater POME partial pressure promoted its steam reforming and water gas shift, which enhanced catalytic performance. Beyond optimum _VPOME (0.09 mL/min), coke-forming Boudouard reaction deteriorated catalytic activity. Catalytic performance was boosted for a longer residence time at higher Wcat (0.1e0.3 g); nonetheless, it was reduced by agglomerated catalyst when Wcat > 0.3 g. Finer LaNiO3 (dcat > 74 mm) with greater surface area to volume ratio exhibited better performance; however, ultrafine LaNiO3 (dcat < 74 mm) had poor performance because of occluded pores. Remarkably, optimized POME steam reforming over LaNiO3 (T ¼ 873 K, _VPOME ¼ 0.09 mL/min,Wcat ¼ 0.3 g, dcat ¼ 74e105 mm) has generated 132.47 mmoL/min of H2-rich syngas, whilst achieved 99.53% XCOD, 99.88% XA, 99.75% XBOD5, and 100% XTSS

Facile synthesis of CaFe2O4 for visible light driven treatment of polluting palm oil mill effluent: Photokinetic and scavenging study

In this paper, a facile synthesis method for CaFe2O4 is introduced that produces a catalyst capable of significant photocatalytic degradation of POME under visible light irradiation. The co-precipitation method was used to produce two catalysts at calcination temperatures of 550 °C and 700 °C dubbed CP550 and CP700. CP550 demonstrated the maximum COD removal of 69.0% at 0.75 g/L catalyst loading after 8 h of visible light irradiation which dropped to 61.0% after three consecutive cycles. SEM images indicated that the higher calcination temperature of CP700 led to annealing which reduced the pore volume (0.025 cm3/g) and pore diameter (10.3 nm) while simultaneously creating a smoother and more spherical surface with lower SBET (9.73 m2/g). In comparison, CP550 had a rough hair-like surface with higher SBET (27.28 m2/g) and pore volume (0.077 cm3/g) as evidenced by BET analysis. XRD data indicated the presence of CaFe5O7 in the CP550 composition which was not present in CP700. The presence of Wustite-like FeO structures in CaFe5O7 are likely the cause for lower photoluminescence intensity profile and hence better charge separation of CP550 as these structures in CaFe2O4 have been known to increase resistivity and electron localization. The COD removal of CP550 dropped from 69.0% to just 7.0% upon adding a small quantity of isopropanol into the reaction mixture indicating hydroxyl radicals as the primary reactive oxidative species