Review on Biodiesel Production from Various Feedstocks Using 12-Tungstophosphoric Acid (TPA) as a Solid Acid Catalyst Precursor

Solid acid catalysts are an important class of catalysts because of their applications in various organic reactions. A 12-tungstophosphoric acid (TPA) is a member of heteropoly acid (HPA) compounds, which grabbed attention because of its low volatility, low corrosivity, higher activity, and acidity compared to sulfuric acid. However, the major problems of using TPA are its solubility in polar media, and its lower surface area. Therefore, various techniques are applied to use it as heterogeneous catalysts. Biodiesel is a diesel substitute renewable fuel, which is produced from various renewable feedstocks through transesterification or esterification reactions. Acid catalysts can catalyze both transesterification and esterification reactions. For this reason, research has been conducted to study the catalytic activity of various TPA precursory solid acid catalysts for biodiesel production. In this Review, a data mining technique has been applied to extract valuable information from the previously published literature. For this purpose, an artificial neural network (ANN) model has been developed based on the published research data to capture the general trends or to make predictions. Both catalyst properties and reaction conditions are trended and predicted using the network model

Enhanced CO₂ Adsorption Using MgO-Impregnated Activated Carbon: Impact of Preparation Techniques

The development of a facile and sustainable approach to produce magnesium oxide (MgO) activated carbons impregnated through a single-step activation of biochar is reported. In a single-step activation process, biochar is impregnated with 3 and 10 wt % of magnesium salt solutions followed by steam activation. In a two-step method, activated carbon, the product of steam activation of biochar, is impregnated with magnesium salt using the incipient wetness and excess solution impregnation process and calcined. The impacts of activation method, impregnation method, and metal content are evaluated, and the product qualities are compared in terms of porosity and surface chemistry. The sorbents are then used for CO2 capture in low partial pressure of CO2 at 25 and 100 °C from a feed containing 15% CO2 in N2 in a fixed-bed reactor. The incipient wetness of activated carbons results in the highest CO2 uptake (49 mg/g) at 25 °C, while single-step impregnation of biochar with rinsing step yields the largest surface area (760 m2/g) and the second highest CO2 uptake (47 mg/g). The increase in Mg content from 3 to 10 wt % results in the smaller surface area and higher CO2 uptake suggesting that the metal content has a greater impact than porosity and surface area. Rinsing the Mg impregnated activated carbon with water results in the larger surface area and higher CO2 uptake in all samples. Moreover, the CO2 adsorption runs at 100 °C shows a 65% increase using MgO impregnated activated carbon as compared to steam activated carbon indicating that MgO impregnation of activated carbon can overcome the limitation of using nontreated activated carbon at moderate operating temperature of 100 °C and low partial pressure of CO2 of 15 mol %

Meso-Structured HPW-MAS‑7 and HPW-MAS‑9 Composite Catalysts for Biodiesel Synthesis from Unrefined Green Seed Canola Oil

H3PW12O40-MAS-7 and H3PW12O40-MAS-9 composite catalysts exhibiting different structural orderings were assembled from zeolite beta and ZSM-5 precursors by a one-pot template-assisted self-assembly mechanism. Characterization results suggest that H3PW12O40 was encapsulated into the mesoporous framework of the aluminosilicates without alteration of mesoporosity of the composites. The sequential introduction of H3PW12O40 during the synthesis of MAS-7 and MAS-9 affected the surface morphologies. The textural characteristics of the composites were improved owing to the introduction of HPW after the addition of an inorganic precursor to the template leading to a material with a high BET surface area. As novel heterogeneous solid acid catalysts, the activity of the composites was determined for the biodiesel synthesis from the unrefined green seed canola oil, giving 95.4 ± 1.4 wt % methyl ester in 10 h at 180 °C with 5.5 wt % of catalyst and a 15.5:1 methanol to oil molar ratio. The recyclability of the composites is evaluated through four consecutive reactions

Adsorptive Removal of Nitrogen, Sulfur, and Aromatic Compounds from Gas Oil by Poly(glycidy methacrylate) Using Two Kinds of Graft Polymerization Methods

Based on a polyglycidyl methacrylate-<i>co</i>-ethylene glycol dimethacrylate copolymer (PGMA-<i>co</i>-EGDMA), nitrogen, sulfur, and aromatic compounds were removed from light and heavy gas oil feeds. The method in which PGMA-<i>co</i>-EGDMA is synthesized can influence the textural and chemical characteristics of the polymer and thus its adsorption capacity. Studies have shown that using cerium initiated graft polymerization in PGMA-<i>co</i>-EDGMA synthesis can improve the adsorption capacity of the polymer. In this work, nitrogen, sulfur, and aromatics removal capacity of (PGMA-<i>co</i>-EGDMA) polymer incorporated with tetranitrofluorenone (TENF) via 1,3 diaminopropane (PDA) using cerium initiated graft polymerization were compared with the same polymer without using cerium. A third polymer with different linker, ethylenediamine (EDA) instead of PDA, was synthesized using cerium initiated graft polymerization to inspect the impact of the linker on the removal efficiency. The synthesized polymers were characterized using different characterization methods. The synthesized polymers were tested at different nitrogen, sulfur, and aromatic content using light and heavy gas oil feeds. In addition, the removal capacity of the synthesized polymers toward nonbasic nitrogen were determined using automatic potentiometric titrator. Results have shown that using cerium graft polymerization on the synthesis of PGMA-<i>co</i>-EGDMA polymer reduced surface area, pore size and volume, and amount TENF grafted, thus decreasing the removal efficiency of nitrogen, sulfur, and aromatics. However, polymer selectivity toward nonbasic nitrogen was not affected by cerium graft polymerization. Furthermore, the adsorption capacity of the PGMA-<i>co</i>-EGDMA decreased with increasing linker length due to steric hindrance effect that influences the adsorption capacity of the polymer

Experimental and Modeling Studies of Torrefaction of Spent Coffee Grounds and Coffee Husk: Effects on Surface Chemistry and Carbon Dioxide Capture Performance

Torrefaction of biomass is a promising thermochemical pretreatment technique used to upgrade the properties of biomass to produce solid fuel with improved fuel properties. A comparative study of the effects of torrefaction temperatures (200, 250, and 300 °C) and residence times (0.5 and 1 h) on the quality of torrefied biomass samples derived from spent coffee grounds (SCG) and coffee husk (CH) were conducted. An increase in torrefaction temperature (200–300 °C) and residence time (0.5–1 h) for CH led to an improvement in the fixed carbon content (17.9–31.8 wt %), calorific value (18.3–25 MJ/kg), and carbon content (48.5–61.2 wt %). Similarly, the fixed carbon content, calorific value, and carbon content of SCG rose by 14.6–29 wt %, 22.3–30.3 MJ/kg, and 50–69.5 wt %, respectively, with increasing temperature and residence time. Moreover, torrefaction led to an improvement in the hydrophobicity and specific surface area of CH and SCG. The H/C and O/C atomic ratios for both CH- and SCG-derived torrefied biomass samples were in the range of 0.93–1.0 and 0.19–0.20, respectively. Moreover, a significant increase in volatile compound yield was observed at temperatures between 250 and 300 °C. Maximum volatile compound yields of 11.9 and 6.2 wt % were obtained for CH and SCG, respectively. A comprehensive torrefaction model for CH and SCG developed in Aspen Plus provided information on the mass and energy flows and the overall process energy efficiency. Based on the modeling results, it was observed that with increasing torrefaction temperature to 300 °C, the mass and energy yield values of the torrefied biomass samples declined remarkably (97.3% at 250 °C to 67.5% at 300 °C for CH and 96.7% at 250 °C to 75.1% at 300 °C for SCG). The SCG-derived torrefied biomass tested for CO2 adsorption at 25 °C had a comparatively higher adsorption capacity of 0.38 mmol/g owing to its better textural characteristics. SCG would need further thermal treatment or functionalization to tailor the surface properties to attract more CO2 molecules under a typical post-combustion scenario

Tri-reforming of CH₄ over a Thermally Stable and Carbon-Resistant Nanonickel Metal Catalyst Dispersed on Mesoporous-Zirconia

A novel nanonickel metal catalyst dispersed on mesoporous-zirconia is developed for the controlled production of the synthesis gas with an H2/CO molar ratio of 1.5–2 via the tri-reforming of methane (TRM). The catalysts were tested in a fixed-bed reactor at 600–850 °C and 1 atm. At the optimum feed (CH4/CO2/O2/H2O/N2) ratio of 1:0.5:0.1:0.0125:1, the maximum CO2 and CH4 conversion was ∼28 and ∼86%, respectively, over the 5 wt % Ni/ZrO2. At this condition, the syngas with an H2/CO ratio of ∼1.5 was achieved at a lower reaction temperature of 700 °C. The superior activity of this catalyst was due to the presence of highly dispersed and reduced nickel particles over the combined tetragonal and monoclinic phases of mesoporous ZrO2. The basic strength of the catalyst, the nickel particle size, and metal dispersion played vital roles in controlling the TRM activity as well as the H2/CO ratio. The time-on-stream study and the used catalyst characterization results established that the nanosized nickel metal particles dispersed on mesoporous zirconia were thermally stable and coke-resistant

Effect of Pretreatment on Physicochemical Properties and Performance of Multiwalled Carbon Nanotube Supported Cobalt Catalyst for Fischer–Tropsch Synthesis

The influence of different nitric acid concentrations (35, 50, 70 wt %) on the physicochemical properties of multiwalled carbon nanotube was investigated. 15 wt % cobalt was impregnated on acid treated nanotubes. The corresponding catalysts were characterized by BET, XRD, Raman, SEM, TEM, TPR, CO chemisorption techniques to further study the impact of acid functionalization on textual properties, metal dispersion, crystallite size, defect generation, and reducibility of 15Co/CNT catalysts. The performance of prepared catalysts was tested for 30% CO and 60% H₂ with balanced Ar in a fixed bed microreactor for Fischer–Tropsch synthesis at 220 °C, 2 MPa, and GHSV of 3000 cm³·g^–1·h^–1. Pretreatment of CNTs with 70 wt % nitric acid exhibited improved physicochemical properties of 15Co/CNT catalyst and hydrocarbon yield by 35% as compared to untreated CNT supported catalyst

Graft Copolymerization of Glycidyl Methacrylate and Ethylene Glycol Dimethacrylate on Alumina for the Removal of Nitrogen and Sulfur Compounds from Gas Oil

Functionalized polymers were synthesized and applied in removing nitrogen and sulfur compounds from gas oils. In this work, the polyglycidyl methacrylate-co-ethylene glycol dimethacrylate polymer incorporated with tetranitrofluorenone, PGMA-DAP-TENF, was synthesized with and without alumina support. Different techniques were used to characterize the synthesized polymers including Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller method, dynamic light scattering, thermogravimetry/differenial thermal analyzer, carbon hydrogen nitrogen sulfur elemental analysis, and field emission scanning electron microscopy. The performance of the polymer with alumina, Al-PGMA-DAP-TENF, was compared to that without alumina using light gas oil. In addition, heavy gas oil feed was used to confirm the adsorption behavior of both polymers in a higher nitrogen and sulfur environment. The effect of adsorption time and temperature was tested using a 1:5, by weight, polymer to feed ratio. Results have shown that alumina particles enhanced the nitrogen removal efficiency of PGMA-DAP-TENF polymer while sulfur removal efficiency was not affected. The nitrogen removal efficiency of Al-PGMA-DAP-TENF polymer was more than twice that of PGMA-DAP-TENF polymer in LGO feed, and twice that in HGO feed. This was due to the higher surface area of Al-PGMA-DAP-TENF polymer, 202 m2/g, compared to that of PGMA-DAP-TENF polymer, 27 m2/g. In addition, Al-PGMA-DAP-TENF polymer removed more basic nitrogen compounds than PGMA-DAP-TENF polymer. This was attributed to the acidic nature of alumina particles that enhance the adsorption of basic nitrogen compounds present in gas oil feeds

Image1_Synthesis of Biochar From Lignocellulosic Biomass for Diverse Industrial Applications and Energy Harvesting: Effects of Pyrolysis Conditions on the Physicochemical Properties of Biochar.TIF

The excessive dependency on fossil fuel resources could be curtailed by the efficient conversion of lignocellulosic biomass. Biochar, a porous carbonaceous product synthesized exploiting thermochemical conversion pathway, could be an environment-friendly replacement of fossil fuel resources. Slow pyrolysis, a sub-class among various thermochemical conversion techniques, has gained immense popularity owing to its potential to convert biomass to biochar. Furthermore, biochar obtained as the by-product of slow pyrolysis has attracted enormous popularity due to its proven role and application in the multidisciplinary areas of engineering and environmental remediation applications. The physicochemical quality of biochar and its performance is significantly dependent on the feedstock type and pyrolysis process parameters. Therefore, further experimental research and investigations in terms of lignocellulose biomass type and pyrolytic process parameters (temperature, heating rate and reaction time) are essential to produce biochar with desired physicochemical features for effective utilization. This review presents an updated report on slow pyrolysis of lignocellulosic biomass, impact of different pyrolysis parameters and degradation pathway involved in the evolution properties of biomass. The influence of the feedstock type and lignocellulosic composition on the biochar properties are also discussed meticulously. The co-relationship between biochar yield at different pyrolysis temperatures and the development of textural properties provides valuable information for their effective utilization as a functional carbon material. Additionally, an extensive study was undertaken to collate and discuss the excellent physicochemical characteristics of biochar and summarizes the benefits of biochar application for diverse industrial purposes. Biochar is acknowledged for its excellent physicochemical properties owing to the thermal treatment and as a result its prospective diverse industrial applications such as for soil treatment, carbon sequestration, adsorbent (wastewater treatment or CO2 capture), producing activated carbon for gold recovery, energy storage and supercapacitor are summarized systematically in this review paper. For instance, biochar when applied in soil have shown improvement in soil respiration by 1.9 times. Furthermore, biochar when used to capture CO2 from flue gas stream under post-combustion scenario has demonstrated superior capture performance (2.8 mmol/g) compared to commercial activated carbon. This paper identified the knowledge gaps and outlooks in the field of the advancements of biochar from slow pyrolysis for targeted engineering applications mainly in the field of environmental remediation and energy harvesting.</p