Structural and thermal investigation of lignocellulosic biomass conversion for enhancing sustainable imperative in progressive organic refinery paradigm for waste-to-energy applications.

The depletion of finite fossil fuel reserves and the severe environmental degradation resulting from human activities have compelled the expeditious development and application of sustainable waste to energy technologies. To encapsulate energy and environment in sustainability paradigm, bio waste based energy production is need to be forged in organic bio refinery setup. According to world bioenergy association, biomass can cover 50 % of the primary energy demand of the world. Therefore, the present study focuses on reforming the energy mix for a clean energy generation, where, sample composition of cotton stalk was acidified in dilute (5% wt.) hydrochloric acid (HCL) for analyzing material burnout patterns in biomass conversion systems utilized in organic bio refinery sector. Advanced thermochemical burning technique, which includes pyrolysis and combustion was applied at four different leaching times from 0 to 180 min under nitrogen environment from 0 °C to 500 °C and air from 500 °C to 900 °C, respectively. Different analyses including proximate, ultimate, gross calorific value (GCV), thermos-gravimetric, kinetic, XRD, FTIR, SEM-EDS were used for analyzing the degradation of demineralized cotton stalk at different treatment rates. Proximate study demonstrated that cotton stalk leaching for 180 min has efficiently infused HCL, leading in a significant increase in fixed carbon and higher heating value of 20.23 % and 12.48%, respectively, as well as a reduction in carbon footprint of around 54.80%. The findings of proximate was validated by GCV analysis and CHNS analysis as value of carbon and hydrogen has shown increasing behavior with the time delay in demineralization Thermo-gravimetric and derivative thermo-gravimetric data analyses shows an increasing trend of conversion efficiency, with the maximum increase of 98 % reported for sample 3H.TT.DEM. XRD characterization has reported 23° to 25° angle for all the observed peaks. Sample 3H.TT.DEM has shown maximum angle inclination along with matured crystalline peak. The latter observations has been validated by FTIR spectroscopy as sample 3H.TT.DEM has reported maximum O-H group formation. Sample 3H.TT.DEM has reported lowest activation energy of 139.51 kJ*mole-1 and lowest reactivity of 0.000293649%*min 0C, due to moderate and stable reactiveness. In SEM examination, increment in pore size and number of pores within the structural matrix of cotton stalk was observed with the enhancement in acidulation process. Furthermore, in EDS analysis, 3H.TT.DEM has shown most balanced distribution of the elements. In this research, sustainable transformation of biomass is envisioned to improve the waste bio refinery system, significantly contributing to the achievement of Sustainable Development Goals 7, 12 and 13.

Core-shell nanostructured Cu-based bi-metallic electrocatalysts for co-production of ethylene and acetate.

Direct electrocatalytic CCU routes to produce a myriad of valuable chemicals (e.g., methanol, acetic acid, ethylene, propanol, among others) will allow the chemical industry to shift away from the conventional fossil-based production. Electrofuels need to go beyond the current electroreduction of CO2 to CO, and we will here demonstrate the continuous flow electroreduction of syngas (i.e., CO and H2), which are the products from CO2-to-CO, with enhanced product selectivity (∼90% towards ethylene). To overcome current drawbacks, including bicarbonate formation that resulted in low CO2 utilisation and low C2+ product selectivity, the development of nanostructured core-shell bi-metallic electrocatalysts for direct electrochemical reduction of syngas to C2+ is proposed. Electrosynthesis of ethylene is performed in a state-of-the-art continuous flow three-compartment cell to produce ethylene (cathodic gas phase product) and acetate (cathodic liquid phase product), simultaneously.

Low-Temperature Toluene Oxidation on Fe-Containing Modified SBA-15 Materials.

Transition metals as catalysts for total VOC oxidation at low temperatures (150-280 °C) are a big challenge nowadays. Therefore, iron-modified SBA-15, AlSBA-15, and ZrSBA-15 materials with 0.5 to 5.0 wt.% Fe loading were prepared and tested for toluene oxidation. It was found that increasing Fe loading significantly improved the rate of oxidation and lowered the temperature of achieving 100% removal of toluene from above 500 °C for the supports (AlSBA-15 and ZrSBA-15) to below 400 °C for 5FeZrSBA-15. The formation of finely dispersed iron oxide active sites with a particle size less than 5 nm was observed on all the SBA-15, AlSBA-15, and ZrSBA-15 supports. It was found that the surface properties of the mesoporous support due to the addition of Al or Zr predetermined the type of formed iron oxide species and their localization on the support surface. Fe-containing SBA-15 and AlSBA-15 showed activity in total toluene oxidation at higher temperatures (280-450 °C). However, 5 wt. % Fe-containing ZrSBA-15 showed excellent activity in the total oxidation of toluene as a model VOC at lower temperatures (150-380 °C) due to the synergistic effect of Fe-Zr and the presence of accessible and stable Fe2+/Fe3+ active sites.

A ruthenium cis-dihydride with 2-phosphinophosphinine ligands catalyses the acceptorless dehydrogenation of benzyl alcohol.

The first ruthenium dihydride complex featuring a phosphinine ligand cis-[Ru(H)2(2-PPh2-3-Me-6-SiMe3-PC5H2)2] was synthesised exclusively as the cis-isomer. When formed in situ from the reaction of cis-[Ru(Cl)2(2-PPh2-3-Me-6-SiMe3-PC5H2)2] with two equivalents of Na[BHEt3], as demonstrated by 31P and 1H NMR spectroscopy, the catalysed acceptorless dehydrogenation of benzyl alcohol was observed leading to benzyl benzoate in up to 70% yield.

Modification of acidic and textural properties of a sulphated zirconia catalyst for efficient conversion of high-density polyethylene into liquid fuel.

Consumption of plastic has a rapid increase of about 8% per annum and reached to 400 million per tonnes approximately, where about 50% of plastic was disposed after using only once. Different techniques for treating this increased waste faced a number of issues related to cost and environmental and sustainable development. Catalytic conversion has been found as one of the most viable solutions to solve this problem. Sulphated zirconia (SZ) catalyst modified with calcium carbide (CC) was found to improve high-density polyethylene (HDPE) conversion into liquid fuel. The liquid content was improved from 39.0wt% to 66.0wt% at 410 °C. HDPE was converted 100% by weight using, SZ/CC with 66wt% liquid yield as compared to the conversion of approximately 98wt% with about 40wt% only liquid yield for the pure SZ. The composition of hydrocarbon liquid product was significantly changed from paraffin (16%) and aromatic (58%) to olefin (74%) and naphthenic (23%) compounds. This significant increase in liquid was related to changes in the acidic and textural characteristics of the new hybrid catalyst, SZ/CC where the total ammonia desorption of 337.0 µm NH3/g for the SZ was modified to 23.4 µm NH3/g for the SZ/CC. Both SZ and SZ/CC catalysts showed characteristics of mesoporous material, where the internal pore volume of SZ had reduced from 0.21 mL/g for SZ to 0.04 mL/g for SZ/CC. Furthermore, XRD analysis indicated the presence of a new compound, CaZrO3 in the SZ/CC, which confirmed a chemical interaction between the SZ and CC through sintering of ZrO2 and CaO. Therefore, the SZ/CC catalyst improves the liquid yield significantly and the selectivity towards olefinic and naphthenic compounds.

Theoretical Efficiency Limits of Photoelectrochemical CO2 Reduction: A Route-Dependent Thermodynamic Analysis.

Solar-fuel formation via photoelectrochemical (PEC) routes using water and CO2 as feedstock has attracted much attention. Most PEC CO2 reduction studies have been focused on the development of novel photoactive materials; however, there is still a lack of understanding of the key limiting factors of this process. In this study, the theoretical limits of Solar-to-Fuel (STF) efficiencies of single- and dual-junction photo-absorbing materials are illustrated for single-step multi-electron CO2 reduction into fuels including HCOO- , CO, CH3 OH and C2 H5 OH. It is also highlighted that STF efficiency depends on the route of two-step PEC CO2 reduction process using CH3 OH as a model fuel. Finally, it is illustrated the beneficial role of alternative strategies such as dual-junction photo-absorbing electrodes, externally applied bias and subsequent reactor chambers on the maximum theoretical efficiencies of PEC CO2 reduction.

A microfluidic photoelectrochemical cell for solar-driven CO2 conversion into liquid fuels with CuO-based photocathodes.

Utilising photoelectrochemical (PEC) devices to produce sustainable fuels from water and CO2 is a very attractive strategy, in which sunlight is used to convert the greenhouse gas (CO2) into a usable form of stored chemical energy. While significant progress has been made in the development of efficient photoactive catalysts for PEC reactions, limited efforts have been focused on the reactor design where continuous flow microfluidic PEC reactors are particular promising. In this work, a range of CuO-based thin films were used as photocathodes in a continuous flow microfluidic PEC reactor using CO2-saturated aqueous NaHCO3 solution under simulated AM 1.5 solar irradiation for up to 12 h. The highest photocurrent density obtained was for the α-Fe2O3/CuO photoelectrode yielding -1.0 mA cm-2 at 0.3 V vs. RHE and initial results indicated a solar-to-fuel (STF) efficiency of 0.48%. While the CuO, Cu2O and CuO-Cu2O photoelectrodes virtually only formed formate, the bilayer α-Fe2O3/CuO photocathode produced methanol in addition to formate indicating that combined copper and iron oxides in continuous flow microfluidic PEC cells have great potential of direct solar conversion into useful chemicals.

In-situ regeneration of activated carbon with electric potential swing desorption (EPSD) for the H2S removal from biogas.

In-situ regeneration of a granular activated carbon was conducted for the first time using electric potential swing desorption (EPSD) with potentials up to 30 V. The EPSD system was compared against a standard non-potential system using a fixed-bed reactor with a bed of 10 g of activated carbon treating a gas mixture with 10,000 ppm H2S. Breakthrough times, adsorption desorption volume, capacities, effect of regeneration and desorption kinetics were investigated. The analysis showed that desorption of H2S using the new EPSD system was 3 times quicker compared with the no potential system. Hence, physical adsorption using EPSD over activated carbon is efficient, safe and environmental friendly and could be used for the in-situ regeneration of granular activated carbon without using a PSA and/or TSA system. Additionally, adsorption and desorption cycles can be obtained with a classical two column system, which could lead towards a more efficient and economic biogas to biomethane process.

Bio-methane from an-aerobic digestion using activated carbon adsorption.

There is an increasing global demand for carbon-neutral bio-methane from an-aerobic digestion (AD) to be injected into national gas grids. Bio-gas, a methane -rich energy gas, is produced by microbial decomposition of organic matter through an-aerobic conditions where the presence of carbon dioxide and hydrogen sulphide affects its performance. Although the microbiological process in the AD can be tailored to enhance the bio-gas composition, physical treatment is needed to convert the bio-gas into bio-methane. Water washing is the most common method for upgrading bio-gas for bio-methane production, but its large use of water is challenging towards industrial scale-up. Hence, the present study focuses on scale-up comparison of water washing with activated-carbon adsorption using HYSYS and Aspen Process Economic Analyzer. The models show that for plants processing less than 500 m3/h water scrubbing was cost effective compared with activated carbon. However, against current fossil natural-gas cost of about 1 p/kWh in the UK both relied heavily on governmental subsidies to become economically feasible. For plants operating at 1000 m3/hr, the treatment costs were reduced to below 1.5 p/kWh for water scrubbing and 0.9 p/kWh for activated carbon where the main benefits of activated carbon were lower capital and operating costs and virtually no water losses. It is envisioned that this method can significantly aid the production of sustainable bio-methane.

Sorption and phase distribution of ethanol and butanol blended gasoline vapours in the vadose zone after release.

The sorption and phase distribution of 20% ethanol and butanol blended gasoline (E20 and B20) vapours have been examined in soils with varying soil organic matter (SOM) and water contents via laboratory microcosm experiments. The presence of 20% alcohol reduced the sorption of gasoline compounds by soil as well as the mass distribution of the compounds to soil solids. This effect was greater for ethanol than butanol. Compared with the sorption coefficient (Kd) of unblended gasoline compounds, the Kd of E20 gasoline compounds decreased by 54% for pentane, 54% for methylcyclopentane (MCP) and 63% for benzene, while the Kd of B20 gasoline compounds decreased by 39% for pentane, 38% for MCP and 49% for benzene. The retardation factor (R) of E20 gasoline compounds decreased by 53% for pentane, 53% for MCP and 48% for benzene, while the R of B20 gasoline compounds decreased by 39% for pentane, 37% for MCP and 38% for benzene. For all SOM and water contents tested, the Kd and R of all gasoline compounds were in the order of unblended gasoline > B20 > E20, indicating that the use of high ethanol volume in gasoline to combat climate change could put the groundwater at greater risk of contamination.

Bio-oil deoxygenation by catalytic pyrolysis: new catalysts for the conversion of biomass into densified and deoxygenated bio-oil.

This work proposes an innovative catalytic pyrolysis process that converts bio-refinery residues, such as spent grains, into intermediate bio-oil with improved properties compared to traditional bio-oils, which allows the use of existing crude-oil refinery settings for bio-oil upgrading into fuels. The integration of bio-oil into a crude-oil refinery would decrease the economic disadvantage of biomass compared to fossil fuels. The catalytic pyrolysis was able to produce bio-oil with a lower O and N content and high levels of aliphatics and H by using activated serpentine and olivine at 430-460 °C. The activated materials seem to be beneficial to the bio-oil energy content by increasing it from less than 20 MJ kg(-1) in the original biomass to 26 MJ kg(-1). Approximately 70-74 % of the starting energy remains in the bio-oil using activated olivine (ACOL) and activated serpentine (ACSE) at 430 °C, whereas only 52 % is retained using alumina (ALU) at the same temperature. There was a strong reduction of the O content in the bio-oils, and the deoxygenation power decreased in the following order: ACOL>ACSE>ALU. In particular, ACOL at 430-460 °C was able to reduce the O content of the bio-oil by 40 %. The oxygenated bio-oil macromolecules interact in the catalyst's active sites with the naturally present metallic species and undergo decarboxylation with the formation of C(5)-C(6) O-depleted species.

Bio-oil and bio-char from low temperature pyrolysis of spent grains using activated alumina.

The pyrolysis of wheat and barley spent grains resulting from bio-ethanol and beer production respectively was investigated at temperatures between 460 and 540 °C using an activated alumina bed. The results showed that the bio-oil yield and quality depend principally on the applied temperature where pyrolysis at 460 °C leaves a bio-oil with lower nitrogen content in comparison with the original spent grains and low oxygen content. The viscosity profile of the spent grains indicated that activated alumina could promote liquefaction and prevent charring of the structure between 400 and 460 °C. The biochar contains about 10-12% of original carbon and 13-20% of starting nitrogen resulting very attractive as a soil amendment and for carbon sequestration. Overall, value can be added to the spent grains opening a new market in bio-fuel production without the needs of external energy. The bio-oil from spent grains could meet about 9% of the renewable obligation in the UK.