A promising catalyst based on a biomass pyrolysis by-product, biochar, has been developed for the production of biodiesel showing effective catalytic activity in transesterification and ...esterification reactions.
A promising catalyst based on a biomass pyrolysis by-product, biochar, has been developed for the production of biodiesel. Two carbon-based solid acid catalysts were prepared by sulfonating pyrolysis char with concentrated or fuming sulfuric acids. Prepared catalysts were studied for their ability to catalyze transesterification of vegetable oils and esterification of free fatty acids. The catalyst sulfonated with the concentrated sulfuric acid demonstrated considerable conversion in free fatty acid esterification, while indicating limited transesterification activity. Using the stronger sulfonating reagent, fuming sulfuric acid, resulted in much higher transesterification activity. Further investigation of the latter catalyst was conducted to determine the effect of sulfonation time (5 and 15
h) and surface area on the transesterification reaction. The surface area of the biochar was increased by chemical treatment using 10
M potassium hydroxide through porosity development. The resulting four catalysts were compared for their catalytic activity. Results showed the catalyst with the highest surface area and acid density to have the highest catalytic activity for the production of biodiesel from canola oil in the presence of methanol as the reagent. Furthermore, the catalyst with the higher surface area indicated higher transesterification activity among the catalyst with similar acid densities. The effects of alcohol to oil (A:O) molar ratio, reaction time and catalyst loading on the esterification reaction catalyzed by the sulfonated biochar were also investigated. Free fatty acid (FFA) conversion increased with increasing A:O molar ratio, reaction time and catalyst loading. The catalyst has a tremendous potential to be used in a process converting a high FFA feedstock to biodiesel.
The cost associated with the disposal of phosphate-rich sludge, the stringent regulations to limit phosphate discharge into aquatic environments, and resource shortages resulting from limited ...phosphorus rock reserves, have diverted attention to phosphorus recovery in the form of struvite (MAP: MgNH4PO4·6H2O) crystals, which can essentially be used as a slow release fertilizer. Fluidized-bed crystallization is one of the most efficient unit processes used in struvite crystallization from wastewater. In this study, a comprehensive mathematical model, incorporating solution thermodynamics, struvite precipitation kinetics and reactor hydrodynamics, was developed to illustrate phosphorus depletion through struvite crystal growth in a continuous, fluidized-bed crystallizer. A thermodynamic equilibrium model for struvite precipitation was linked to the fluidized-bed reactor model. While the equilibrium model provided information on supersaturation generation, the reactor model captured the dynamic behavior of the crystal growth processes, as well as the effect of the reactor hydrodynamics on the overall process performance. The model was then used for performance evaluation of the reactor, in terms of removal efficiencies of struvite constituent species (Mg, NH4 and PO4), and the average product crystal sizes. The model also determined the variation of species concentration of struvite within the crystal bed height. The species concentrations at two extreme ends (inlet and outlet) were used to evaluate the reactor performance. The model predictions provided a reasonably good fit with the experimental results for PO4–P, NH4–N and Mg removals. Predicated average crystal sizes also matched fairly well with the experimental observations. Therefore, this model can be used as a tool for performance evaluation and process optimization of struvite crystallization in a fluidized-bed reactor.
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•Reactor model developed incorporating kinetics, thermodynamics, and hydrodynamics.•Provides process performance evaluation and product crystal size.•Model used for reactor design, optimization, and process control.
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▶ Mesoporous and high surface area glucose char was synthesized. ▶ Mesoporous and high surface area carbon-based catalyst was synthesized. ▶ Carbon catalyst reactivity is dependent on ...acidity but independent of surface area.
Mesoporous carbon catalysts have received considerable interest in the scientific community because of their tunable porosity, hydrophobic surface, and ease of functionalization with active groups such as –SO
3H. The formation of silica templates is a typical method to prepare a mesoporous carbon, but little is understood on its role for effective sulfonation. In this study, silica templates were used to prepare mesoporous sugar char using the confined activation process. The char was functionalized with –SO
3H groups before or after removing the silica templates. The roles of the silica templates were evaluated based on the physicochemical properties of the catalysts. The results showed that silica templates provided support to the internal porosity, but prevented the –SO
3H groups from effectively reaching the internal surface. The esterification of oleic acid showed that the reactivity of the carbon-based catalysts is dependent on the total acidity, but independent of the surface area. These findings show that carbon-based catalysts are suitable for esterification which is useful for biodiesel production.
Heterogeneous catalysts bearing sulfonic acid groups were prepared using biochar as the carbon support. Biochar samples were first treated with KOH before carbonization at different temperatures ...(450, 675, and 875 °C) then sulfonated using fuming H2SO4 at 150 °C for 15 h. The sulfonated catalysts were characterized using BET surface area and porosity, elemental analysis, total acid density, FT-IR spectroscopy, X-ray diffraction, and thermogravimetric analysis. Catalytic performance was determined via the transesterification of canola oil with methanol. The reaction yield was found to be dependent on both catalyst surface area and total acid density, suggesting that the maximum yield would be obtained for a catalyst prepared from char carbonized between 675 and 875 °C. FT-IR spectra and XRD patterns reveal that higher carbonization temperatures cause an increasing reorientation of the biochar’s carbon sheets toward a more graphite-like structure, decreasing the total acid density despite the increasing surface area. Catalyst reusability was poor under high temperature/pressure conditions.
The present global economy downturn affects every corner of the world including the vehicular fuel industry. This paper highlights some of the perspectives for the biodiesel industry to thrive as an ...alternative fuel, while discussing benefits and limitations of biodiesel. This includes the improvement of the conversion technology to achieve a sustainable process at cheaper cost, environmentally benign and cleaner emissions, diversification of products derived from glycerol, and policy and government incentives. More specifically, an overview is given on making the production process more economical by developing high conversion and low cost catalysts from renewable sources, and utilizing waste oil as feedstock. Further emphasis is given on the need for public education and awareness for the use and benefits of biodiesel, while promoting policies that will not only endorse the industry, but also promote effective land management.
This paper studied the synergistic effects of catalyst mixtures on biomass catalytic pyrolysis in comparison with the single catalyst in a microwave reactor and a TGA. In general, positive ...synergistic effects were identified based on increased mass loss rate, reduced activation energy, and improved bio-oil quality compared to the case with a single catalyst at higher catalyst loads. 10KP/10Bento (a mixture of 10% K
PO
and 10% bentonite) increased the mass loss rate by 85 and 45% at heating rates of 100 and 25°C/min, respectively, compared to switchgrass without catalyst. The activation energy for 10KP/10Bento and 10KP/10Clino (a mixture of 10% K
PO
and 10% clinoptilolite) was slightly lower or similar to other catalysts at 30 wt.% load. The reduction in the activation energy by the catalyst mixture was higher at 100°C/min than 25°C/min due to the improved catalytic activity at higher heating rates. Synergistic effects are also reflected in the improved properties of bio-oil, as acids, aldehydes, and anhydrosugars were significantly decreased, whereas phenol and aromatic compounds were substantially increased. 30KP (30% K
PO
) and 10KP/10Bento increased the content of alkylated phenols by 341 and 207%, respectively, in comparison with switchgrass without catalyst. Finally, the use of catalyst mixtures improved the catalytic performance markedly, which shows the potential to reduce the production cost of bio-oil and biochar from microwave catalytic pyrolysis.
Empowering students and scholars to effectively address complex societal challenges frequently entails embracing unconventional pathways to foster transdisciplinary (TD) education. This empowerment ...is further facilitated by collaborative efforts supported by the TD experience. This paper examines one such initiative: a student-centered, experimental design of a TD doctoral pilot program for environmental sustainability at the University of British Columbia, a large, research-intensive public university in Canada. In this study, we documented shifts in participants’ development and assessed the impact of TD collaboration conditions on the educational design process. The findings indicate that engaging in collaborative TD experiences yields substantial pedagogical benefits, introducing novel opportunities for design and experimentation. This TD space appears to offer conducive conditions for students and faculty to more effectively navigate adaptive and innovative contexts within higher education. Pedagogical experimentation of this nature provides insights that are challenging to derive from theoretical speculation alone, offering potential pathways for today’s learners and educators as they confront complex societal challenges.
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• Process provides simultaneous sorbent reactivation and steam superheating.• Methane-concentrated oxyfuel calciner is assessed for CaCO3/Ca(OH)2 co-calcination.• Conditions for ...autothermal, coke-free and complete sorbent regeneration are studied.
This paper investigates the equilibrium performance of CaO hydration and CaCO3/Ca(OH)2 co-calcination in calcium-looping processes. A novel lime hydration configuration is proposed, introducing saturated steam as the reactivating reagent and direct-heat-removal medium. The proposed hydrator generates a substantial amount of superheated steam, used elsewhere as required. The slaked lime and limestone are calcined simultaneously in a methane-concentrated oxy-fuel calciner. The equilibrium performance of the co-calciner is studied at different reactor temperatures, operating pressures, solid/gas feed ratios and feed compositions. A correlation is proposed which estimates the required gaseous feed composition for autothermal, coke-free and complete sorbent regeneration using this novel technology.
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