Hydrogen production from pyrolysis oil using the steam-iron process: a process design study

The overall energy efficiency of the production of pure hydrogen using the pyrolysis oil driven steam-iron process is evaluated for different process conditions. The process consists of a two-step process (reduction with pyrolysis oil, oxidation with steam) from which pure hydrogen can be obtained, without purification steps. An optimum energy efficiency of 53% is achieved when the equilibrium conversion is obtained in the redox cycle at 800°C. When assuming chemical equilibrium, increasing the process temperature results in a low process efficiency due to a large amount of unreacted steam that needs to be condensed to separate the hydrogen product. Using experimental data in the process simulation, a high-energy efficiency is obtained at 920°C (39%) compared with the efficiency at 800°C (29%). This is caused by the low conversion in the reduction at 800°C. Improving the iron oxide material to enhance the reduction with pyrolysis oil at 800°C, is therefore suggested.     

Comparative life cycle assessment (LCA) of bio-oil production from fast pyrolysis and hydrothermal liquefaction of oil palm empty fruit bunch (EFB)

This paper presents a life cycle assessment of two alternative processes for the production of bio-oil from Malaysian oil palm empty fruit bunch (EFB), namely, fast pyrolysis and hydrothermal liquefaction, in which limited studies have been reported in the literature. In this study, both processes were evaluated and compared in terms of their impacts to the environment, specifically based on the selected impact categories: global warming potential (GWP), acidification, eutrophication, toxicity, and photochemical-oxidant formation. The results indicated that fast pyrolysis process of EFB caused more severe impact on the environment compared to hydrothermal liquefaction process. Fast pyrolysis process caused almost 50 % more GWP impact compared to hydrothermal liquefaction process, due to both high energy demand in the drying process and high-temperature operation of fast pyrolysis. Other than that, the assessment on other environmental impacts indicated that hydrothermal liquefaction operation is more environmentally benign compared to fast pyrolysis due to the reduced energy consumption. Lastly, sensitivity analysis involving three scenarios (change in bio-oil yield, thermal efficiency of boilers, and thermal efficiency of dryers), respectively, were constructed and presented.     

Operating cost study through a Pareto-optimal fuzzy analysis using commercial ferrate (VI) in an ultrasound-assisted oxidative desulfurization of model sulfur compounds

There is a need for transportation fuel such as diesel oil to undergo a desulfurization process prior to its usage in order to comply with stringent environmental regulations. Predominant organic sulfur compounds present in fuel oils comprise benzothiophene (BT) and dibenzothiophene (DBT). High sulfur compound reduction is attainable through a desulfurization process but this often leads to risking higher operating cost due to longer reaction time and the use of large amounts of oxidizing agent and phase transfer agent. Fuzzy logic, which is often used in multi-objective decision-making models, is able to meet the desired objective and satisfy the given constraints at the same time. In this study, a pareto-optimal fuzzy analysis is used in order to determine the best conditions in the ultrasound-assisted oxidative desulfurization process and at the same time achieving the lowest possible operating cost for reducing BT and DBT. Process parameters investigated include ultrasonication time (10–30 min), phase transfer agent (100–300 mg), organic to aqueous phase ratio (10:30–30:10), and ferrate concentration (100–300 ppm) for the reduction of model sulfur compounds. Results through fuzzy optimization indicated optimum results of 93.79 % BT conversion with operating cost of US$ 0.830 and 88.36 % DBT conversion with operating cost of US$ 0.769.     

Cleaner tanning process for the manufacture of upper leathers

There is a growing need for eco-benign tanning systems owing to stringent environmental regulations. In this study, a combination tanning process based on henna and tetrakis hydroxymethyl phosphonium sulphate (THPS) for the production of upper leathers as a cleaner alternative is presented. Extract from the leaves of Lawsonia inermis (henna) has been evaluated for its tanning characteristics in a combination tanning system based on henna and THPS. Both tanning methodologies, henna followed by THPS (henna–THPS) and THPS followed by henna (THPS–henna), have been attempted. It has been observed that THPS–henna combination tanning, employing 20% henna and 1.5% THPS, provides a shrinkage temperature of 96°C. The characteristics of the leathers indicate that the THPS–henna combination system provides leathers with good organoleptic properties and comparable strength properties. The combination system provides significant reduction in the discharge of total dissolved solids in the wastewater. These leathers showed opened up, split compact fiber structure, indicating that the tanning process did not bring about any major change or destruction on the fiber structure of the leathers. The leathers have been further characterized for chemical analysis and scanning electron microscopy. The leathers obtained from the combination system are lighter in color compared to control leathers. Possibility of making upper leathers from THPS–henna combination system as an effective alternative cleaner tanning methodology is established in this work.     

Strategy for waste management in the production and application of biosurfactant through surface response methodology

This study aims to identify the optimal biosurfactant production process via fermentation by Bacillus subtilis, using waste material as alternative substrates (glycerin, water from potatoes processing, corn steep liquor, and frying oil), thereby highlighting the absence of synthetic substrates. A fractional factorial design 2^4?1 was previously used to determine the effects of the concentrations of the four substrates, selecting three of them to be used in a central composite rotatable design (CCRD) 2³. Responses of the emulsifying index after 24 h (EI₂₄) were first evaluated for fermentation in 250-mL flasks. Thus, the concentration of waste material that is able to provide EI₂₄ up to 100 % from 9 % of glycerin and 1 % of potato peel was determined, with subsequent experimental validation at the optimized point. One-liter-bench-batch fermentation with the optimum medium (based on the CCRD) was also carried out. In order to compare, another 1-L-bench-batch fermentation was performed using residual glycerin through the biosurfactant concentrations, dry weight, oxygen dissolved, and pH profile. Evidence of high potential for biosurfactant production (with EI₂₄ 100 % to toluene, 67 % to hexane, and 62 % to soybean oil), which can be suitable for applications in oil recovery was presented.     

Vacuum activation assisted hydrogenation-dehydrogenation for preparing high-quality zirconium powder

The vacuum activation assisted hydrogenation-dehydrogenation (HDH) method was applied to fabricate the high-purity and ultrafine nuclear grade zirconium powders. An additional vacuum activation process was specially used prior to the hydrogenation to suppress the oxygen content and increase the hydrogen content. It was found that this extra process was not only efficient in shortening the length of the whole process, but also critical in improving the quality of Zr powders. The detailed investigations on the mechanism indicated that the merits could be both attributed to the removal of the oxygen sources on the sponge zirconium surface and the formation of micro-cracks on the ZrO₂ film. By adjusting the parameters of the vacuum activation assisted HDH process, the oxygen content of the intermediate material ZrH₂ was decreased down to 0.16 wt.%, while the hydrogen content was increased up to 2.14 wt.%, nearly approaching to the theoretical value. Based on this high-quality ZrH₂ bulks, the Zr powders with oxygen content of 0.21 wt.% and D₅₀ of ~2.9 μm could be fabricated after the ball-milling and dehydrogenation process. An efficient approach to produce high-quality Zr powders was systematically investigated in this paper to satisfy with the demand of the nuclear industry.     

Overview of Biomass Conversion to Electricity and Hydrogen and Recent Developments in Low-Temperature Electrochemical Approaches

Biomass is plant or animal material that stores both chemical and solar energies, and that is widely used for heat production and various industrial processes. Biomass contains a large amount of the element hydrogen, so it is an excellent source for hydrogen production. Therefore, biomass is a sustainable source for electricity or hydrogen production. Although biomass power plants and reforming plants have been commercialized, it remains a difficult challenge to develop more effective and economic technologies to further improve the conversion efficiency and reduce the environmental impacts in the conversion process. The use of biomass-based flow fuel cell technology to directly convert biomass to electricity and the use of electrolysis technology to convert biomass into hydrogen at a low temperature are two new research areas that have recently attracted interest. This paper first briefly introduces traditional technologies related to the conversion of biomass to electricity and hydrogen, and then reviews the new developments in flow biomass fuel cells (FBFCs) and biomass electrolysis for hydrogen production (BEHP) in detail. Further challenges in these areas are discussed.     

Experimental study on operating conditions of 2-ethylhexanol manufacturing process

In this work, hydrogenation of 2-ethyl-3-propylacrolein (EPA) was investigated experimentally using a laboratory-scale plug flow reactor. In this process, 2-ethylhexanol was synthesized using a EPA aldehyde in the presence of vinylpyruvate hydratase catalyst. Next, the effects of operating conditions including temperature, pressure, and species flow rates on its performance were studied within temperature and pressure ranges of 110–160°C and 1–6 bars, respectively. The hydrogen and EPA flow rates were measured to be 150–240?ml/h and 0.03–0.11?ml/h, respectively. The results showed that the optimum yield of 2-ethylhexanol production is achieved at a temperature of 155°C, the pressure of 4.4 bars, and hydrogen flow rate of 192.4?ml/min. Using optimum operating conditions, the process yield was 99.86%, with hydrogen flow rate identified as the most effective parameter on the process yield.     

Preparation of Dark-Red Membrane by Micro-Arc Oxidation on AM50 Alloys

The dark-red membrane was prepared on AM50 magnesium alloys by using chemical conversion and micro-arc oxidation (MAO). The effects of MAO electrolyte and chemical conversion solution were researched through L₉(3⁴) orthogonal test to obtain formulation for the aforementioned process. Surface morphology, composition, and corrosion resistance were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical test. A dark-red membrane can be obtained by the following steps: first, a chemical conversion was carried out on AM50 alloys by placing them in a solution of 50 g/L KMnO₄ and 100 g/L NH₄H₂PO₄ at 50°C for 11 min; second, the prepared alloys were placed into MAO electrolytes containing 10 g/L Na₂SiO₃ and 5 g/L NaOH in order to obtain the dark-red-colored MAO ceramic membranes. The membranes that are mainly composed of SiO₂, MnO, MnP, MgSiO₃, and Mg₂SiO₄ have porous structures. MnO and MnP were identified to be responsible for giving color to the membrane.     

Effect of transition metal on the hydrogen storage properties of Mg–Al alloy

Mg–Al alloys were prepared via sintering combined with ball milling, and the effect of a transition metal (TM = Ti, V, Ni) on the hydrogen storage properties of these alloys was investigated; the alloys were characterized via X-ray diffraction, pressure composition isotherms, and differential scanning calorimetry. The results showed that the alloys were mainly composed of Mg and the Mg₁₇Al₁₂ phase, and the cell volume of these phases decreased after the addition of TM (TM = Ti, V, Ni), which is attributed to the improved hydrogenation kinetics of Mg–Al alloy. Moreover, the hydrogenation/dehydrogenation temperature of the Mg–Al alloy decreased with the addition of TM (TM = Ti, V, Ni). Ti, Ni, and V acted as a catalyst, thereby lowering the reaction barrier for dehydrogenation and promoting the reversible hydrogenation reaction of the Mg–Al alloy. The onset temperature of dehydrogenation of the Mg–Al–V alloy was ~244 °C, which was 66 °C lower than that of the Mg–Al alloy (~310 °C). And the apparent activation energy of the Mg–Al–V alloy was 80.1 kJ mol^?1, where it was 34.6 kJ mol^?1 lower than that of Mg–Al alloy.     

Co-production of power and urea from coal with CO<Subscript>2</Subscript> capture: performance assessment

Coal-based power plants are largest emitter of CO₂ as a single sector. To use fossil fuels (including coal), CO₂ capture and storage is a visible option. But large energy requirement for this process and risk associated with storage of CO₂ demand alternative solutions including recycling of captured CO₂. In this paper, a co-production of power and urea is proposed using coal with captured CO₂. Detailed ASPEN Plus^® model is developed for this plant. As shift reaction for producing H₂ has significant effect on output parameters, analysis is done for two different values of shift reaction, i.e., 90 and 95 % conversion. Plant consumes substantial auxiliary power (~19 % for the base case). Auxiliary power becomes a minimum for about 25 % captured CO₂ utilization for 95 % shift conversion. An economy factor is also defined to estimate the economic advantage of utilizing captured CO₂. Results show that economic advantage is obtained for CO₂ utilization beyond ~5 % for 95 % water gas shift reaction and it is beyond ~10 % for a 90 % shift reaction.     

Hydrogen sorption enhancement in cold-rolled and ball-milled CaNi<Subscript>5</Subscript>

The effect of cold rolling and ball milling on the hydrogen sorption properties of CaNi₅ was investigated with a special emphasis on the first hydrogenation. We compared cold rolling for 5, 12, and 25 rolling passes in the air with ball milling in argon for 30 and 60 min. Results show that 15 min of ball milling had a positive effect on the first hydrogen absorption, but further milling to 60 min made the sample almost impermeable to hydrogen. Cold rolling had a positive effect on first hydrogenation. We found that cold rolling greatly reduces the particle size as well as the crystallite size. We also found that dehydrogenation under 5 kPa of hydrogen at 323 K was not complete. Two partially hydride phases remained: CaNi₅H and Ca₂Ni₇H _x .     

Producing clean diesel fuel by co-hydrogenation of vegetable oil with gas oil

The goal of our investigation was the production of partially bio-derived fuels in the gas oil boiling point range. Our aim was the production of diesel fuel blending components by co-hydrogenation of mixtures of high-sulphur gas oil (about 1.0%) and vegetable oil raw materials with different vegetable oil contents (0, 5, 15, 25 and 100%). The experiments were carried out on a NiMo/Al₂O₃ catalyst with a targeted composition (T = 300–380°C, P = 60–80 bar, LHSV = 1.0/h and H₂/HC = 600 Nm³/m³). We obtained that both the vegetable oil conversion reactions and the gas oil quality improvement reactions took place. Under the favourable operational conditions (360–380°C, P = 80 bar, LHSV = 1.0/h and H₂/HC = 600 Nm³/m³ and up to 15% vegetable oil content of the feed), the main properties of the high-yield (>90%) products except for the Cold Filter Plugging Point (CFPP) value satisfied the requirements of the standard of diesel fuels (EN 590:2009). The amount of vegetable oil higher than 15% reduced the desulphurization efficiency, because of the intake of large quantities of oxygen with the triglyceride molecules of the vegetable oil. The products—depending on the vegetable oil content of the feedstocks—have an increased n- and i-paraffin content, so their combustion properties are very favourable, and the emission of particles is lower.     

Valorisation of mango seed via extraction of starch: preliminary techno-economic analysis

Reducing environmental impacts and obtaining economic benefits based on utilisation of waste materials are drivers for the implementation of cleaner production policies and technologies in food processing industries. Starch is a very versatile material with a wide range of applications in the food, pharmaceutical, textile, paper, cosmetic and construction industries. In Ethiopia, starch is widely used in the textile industry. To meet the starch demand, the country imports approximately 45% of the starch used in the country. Consequently, it is imperative to find additional sources of starch that could substitute for the amount of starch that is currently being imported. Mango seeds, a waste material that is disposed of after consumption of mangos, were studied for potential use as an alternative resource for starch production. The results showed that starch extraction from mango seeds was facile and a good quality product was obtained. The present study is concerned with a techno-economic analysis for industrial production of starch from mango seeds. The study shows that extraction of starch from waste mango seeds is feasible: the project is financially viable with an accounting rate of return of 83% and a break-even analysis of 78% with a payback period of 2 years.     

One pot conversion of furfural to 2-methylfuran in the presence of PtCo bimetallic catalyst

Biomass-derived furfural (FAL) is the platform chemical for synthesis of various value-added chemicals and fuels. One of the FAL-derived chemicals, i.e., 2-methylfuran (2-MF), is the potential biofuel due to its attractive chemical and physical properties. Various methods are reported for conversion of FAL to 2-MF which are operated at high temperature and high H₂ pressure. In present work, one pot catalytic method was developed in batch mode process for conversion of FAL to 2-MF. Reactions are carried out in the presence of PtCo/C bimetallic catalyst under 0.5–1 MPa H₂ pressure. Monometallic and bimetallic catalysts with different Pt and Co loading were prepared by wet impregnation method, and catalysts were characterized by transmission electron microscopy, BET surface area, X-ray photoelectron spectroscopy, X-ray diffraction and inductive coupled plasma atomic emission spectroscopy techniques. 59% 2-MF yield was achieved at 180 °C and lower (0.5 MPa) H₂ pressure.     

Oil Agglomeration of Coal Fines in Continuous Mode of Operation

Coal–oil agglomeration plays a vital role in addressing the ever increasing pollution due to coal utilization apart from minimizing coal-waste generation. Numerous studies were available on coal–oil agglomeration in batch mode; however, the process has been seldom investigated under continuous mode of operation. In the present study, an attempt has been made to examine the coal–oil agglomeration process under continuous mode of operation using high ash power grade coal procured from Jharkhand (India) with Karanja oil as agglomerant. The effectiveness of the process was estimated in terms of organic matter recovery (OMR) and ash rejection (AR). Preliminary experiments were performed under batch mode to optimize the process variables (oil dosage, agitation speed, agglomeration time, and coal particle size). Subsequently, the process was operated in continuous mode under these optimum conditions by varying the reactor residence time. In batch mode, a maximum OMR (78.09%) with significant AR (51.28%) was observed under the following optimized conditions: oil dosage (20% by wt of coal); agitation speed (1,500 rpm); agglomeration time (120 s); and coal particle size (+75–200 µm). However, operation under continuous mode resulted in lower OMR (maximum 47.51%) with higher AR (70.38%), which can be attributed to inadequate contact between coal fines and oil.     

Life cycle assessment of palm-derived biodiesel in Taiwan

In Taiwan, due to the limited capacity of waste cooking oil, palm oil has been viewed as the potential low-cost imported feedstock for producing biodiesel, in the way of obtaining oil feedstock in Malaysia and producing biodiesel in Taiwan. This study aims to evaluate the cradle-to-grave life cycle environmental performance of palm biodiesel within two different Asian countries, Malaysia and Taiwan. The phases of the life cycle such as direct land-use-change impact, plantation and milling are investigated based on the Malaysia case and those of refining, and fuel production as well as engine combustion is based on Taiwan case. The greenhouse gas (GHG) emission and energy consumption for the whole life cycle were calculated as ?28.29 kg CO₂-equiv. and +23.71 MJ/kg of palm-derived biodiesel. We also analyze the impacts of global warming potential (GWP) and the payback time for recovering the GHG emissions when producing and using biodiesel. Various scenarios include (1) clearing rainforest or peat-forest; (2) treating or discharging palm-oil-milling effluent (POME) are further developed to examine the effectiveness of improving the environmental impacts     

Studies on biodegradation of vegetable-based fat liquor-containing wastewater from tanneries

Fat liquoring, a post-tanning operation is carried out on tanned leather using oils, fats, or greases in emulsion form to make soft leathers and to improve the physical characteristics of the finished products during leather manufacturing. Around 10–15 % of un-exhausted fat liquor is discharged in the process water as wastewater. The major components of vegetable fat liquor are triacylglycerols, which primarily consist of glycerol molecules esterified with long chain fatty acids. The presence of fats, grease, and oils not only causes choking of wastewater conveyance mains but also interferes with the oxygen-transfer efficiency in aerobic treatment process. The aim of the present study is to assess the rate of biodegradability of vegetable-based fat liquor-containing wastewater generated from tanneries for various food to microbial (f/m) ratio, i.e., 0.35, 0.25, and 0.15 g biochemical oxygen demand (BOD₅)/g volatile suspended solids (VSSs) day. The f/m ratio and reaction time were investigated in detail in aerobic batch reactor to arrive at the optimum ratio needed for biodegradation of vegetable fat liquor. From the aerobic biodegradation studies, it was established that at an f/m ratio of 0.15 and a reaction time of 24 h, BOD₅ and chemical oxygen demand removals were 97.24 and 89.58 %, respectively. It was evident from Fourier transform infrared spectrometry and electrospray ionization–mass spectroscopy analysis that the triglycerides present in vegetable fat liquor were degraded effectively.     

Biosorption performance,combustion behavior,and leaching characteristics of olive solid waste during the removal of copper and nickel from aqueous solutions

Several researchers have proved that agricultural by-products constitute good adsorbents for removing heavy metals from aqueous solution. However, few investigations have identified efficient strategies for the adsorbent′s regeneration. Hence, a global methodology for the removal of copper and nickel metals from wastewater including metal biosorption, thermal treatment and residual ash landfill is proposed. In order to validate this strategy, olive solid waste (OSW), provided by an olive oil mill from Tunisia, were used to remove copper and nickel on batch experiments. Copper and nickel were adsorbed on a monolayer of OSW surface with maximal adsorption capacity (q _max) of 3.6 and 1.7 mg g^?1, respectively. Contaminated OSW with copper and nickel were combusted at 850 °C in an electrical furnace. About 96 % of each metal was recovered in residual ashes that present a good secondary raw material for copper and nickel production. Low leaching transfers (≤4 %) were observed for copper and nickel from residual ashes leading to the possibility to be landfilled. Therefore, the suggested process can be used as an alternative to the classical technologies for effluent decontamination.     

Hydrogen production of nickel–scandia-stabilized zirconia and copper/nickel–scandia-stabilized zirconia catalysts through steam methane reforming for solid oxide fuel cell operation

In this study, the catalytic activities of the steam methane reforming (SMR) reactions with two catalysts, including nickel–scandia-stabilized zirconia (Ni–SSZ) and copper/nickel–scandia-stabilized zirconia (Cu/Ni–SSZ), were examined and compared. The microstructure and crystallinity of the as-prepared catalysts were characterized by scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. Mass spectrometer was applied in the outlet streams, in order to simultaneously monitor the time-dependent kinetics in the reactor for an activity test and conversion examination. Finally, thermogravimetric analysis (TGA) and Raman spectrometer were implemented for further verification of carbon residuals on the catalysts. It was found that the incorporation of Cu on Ni–SSZ imposed significant constraints on the growth of nickel crystallites from NiO during the annealing process in reducing atmospheres. The methane conversion of Ni–SSZ and Cu/Ni–SSZ catalysts (annealed at 300 °C for 2 h) was 36.2 and 26.0%, respectively. However, the amount of carbon residuals on Cu/Ni–SSZ catalyst (300 °C for 2 h) was 18.6%, which is lower than that of the Ni–SSZ catalysts (33.2%) from TGA results. Further Raman experiments revealed that more graphite-like carbon residuals and less defects or amorphous carbons (I_G/I_D?=?2.0) were found in the case of Cu/Ni–SSZ catalysts (300 °C for 2 h). Among the catalysts in this study, the Cu/Ni–SSZ catalyst (300 °C for 2 h) is considered as a promising catalyst for SMR reaction, since it has a fair methane conversion, and characterized higher CO₂ selectivity and lower CO selectivity without compromising the hydrogen purity. More importantly, the least amount of carbon residuals was found in Cu/Ni–SSZ catalyst (300 °C for 2 h), which assured a better lifetime.