Higher HHV Research Articles

Experimental study of hydrothermal treatment for reducing potassium content on palm oil empty fruit bunch (EFB)

Abstract This study investigated the effects of the potassium content of EFB biochars after hydrothermal treatment (HT). The experiments were carried out in a 3000 mL reactor and treated for 60 min. Two parameters were studied in detail: water (liquid) to EFB (solid) ratio or L/S (5:1 and 10:1) and varied temperature (150, 180, 210, and 230°C). The ash content of biochars decreased gradually due to the increasing temperature, with values varying from 6.55% to 12.79%. The sodium of the treated biochars was removed entirely for each HT process, while the potassium notably reduced with the removal efficiency reached 75.34-93.79%. HT at temperature 230°C was the optimum condition to reduce the Agglomeration Index (AI), which 230H5 and 230H10 resulted in 0.26 and 0.31, respectively. Although the mass yield significantly reduced, the 230H5 was highly recommended when used for co-combustion fuel because it had the highest HHV (21.36 MJ/kg), the lowest AI (0.26), and the high removal efficiency of potassium (93.76%).

Parameter study of waste shiitake substrate/waste polyethylene Co-gasification using Aspen Plus kinetic modeling

Waste Shiitake Substrate, a major agricultural waste in Taiwan, is typically packaged in plastic bags (Waste Polyethylene, PE) during mushroom cultivation process. Consequently, these plastic bags become additional waste that requires proper disposal. In recent years, Taiwan has produced over 150,000 tons of waste shiitake substrate annually, with approximately 1580 tons of plastic bags used for mushroom cultivation. Up to now, there has not been an effective method for handling this waste. This study aims to develop a co-gasification process using the complementary characteristics of WSS and PE. Unlike traditional direct combustion, the co-gasification approach can convert these wastes into cleaner bioenergy. This study aims to develop an Aspen Plus model for a laboratory-scale 1 kWth bubbling fluidized bed gasifier. This model incorporates kinetic reactions and tar formation during co-gasification. The model accurately predicted the experimental results. Different variables were investigated, including gasifier temperature, blending ratio (BR) of the two fuels, mixing ratio (MR) of the gasifying agent, and equivalence ratio (ER). The results showed that hydrogen production correlated positively with the steam-to-carbon ratio in the gasification medium, whereas carbon monoxide (CO) was more affected by the feedstock type and equivalence ratio, with CO reaching its peak at an equivalence ratio of 0.2. When gasifying using only waste shiitake substrate (BR = 0%), at an ER of 0.2, a gasification furnace temperature of 950 °C, and an MR of 100% (pure CO2), the maximum CO mass flow rate in the syngas is obtained. Waste plastics contain significant amounts of volatile matter and no oxygen, leading to increased production of CH4, CO, and H2 during co-gasification with the addition of waste plastic. For plastics, high temperature and low ER conditions promote the production of CO, H2, and CH4 because of the significant tar content, thereby enhancing the Cold gas efficiency (CGE). When the gasification temperature is 950 °C, with 80% polyethylene (BR = 80%) and an ER of 0.1, the highest HHV is achieved. These results can serve as a reference for determining the operational conditions for the scale-up of gasification systems.

Characteristics of rice husk biochar briquettes with municipal solid waste cassava, sweet potato and matooke peelings as binders

Rice husks are not readily biodegradable making their disposal challenging due to the common disposal method of open burning which has negative environmental effects. Additionally, banana, sweet potato and cassava peelings form a large percentage of organic municipal solid waste. Therefore, this study developed rice husk biochar briquettes with organic municipal peelings waste as binders. Rice husks biochar was formed via carbonization processes in a step-down kiln at temperatures ranging between 400 and 500 °C. Organic binders were mixed with the rice husk biochar at different ratios of 10% and 15% before being compacted at a pressure ≤ 7 MPa into briquettes. Thermogravimetric results showed that the developed briquettes had high ash contents ranging from 44% to 47%. Rice husk biochar briquettes with the highest particle density were observed for briquettes with 15% cassava peel binder at 427.1 kg/m3. The highest HHV and maximum attainable flame temperature of 21.75 MJ/kg and 828.7 °C were obtained for rice husk biochar briquettes with 15% matooke peeling organic binder. For all rice husk biochar briquettes, increasing the organic peeling binder had a positive impact of reducing the ash content, while at the same time increasing the peak temperatures, thus contributing to their enhanced thermal stability.

Dehydration and decarboxylation via pyrolysis process of waste oily sludge accumulated at North Refineries Company Baiji for use as a pyro-fuel

Waste oily sludge (WOS) accumulated in a yard was exposed to sunlight and stored randomly from various sources at North Refineries Company Baiji (NRC). This study aims to convert WOS into pyro-fuel via pyrolysis technology via ranges of temperatures and times. First, run; a range of temperature was 250, 450, and 650 °C respectively, feed amount 5 g of WOS, residence time 90 min, under N2 pressure. Second, run; with a range of residence time at 60, 90, and 120 min respectively, with feed amount 5 g, the temperature at 650 °C (optimum temperature found). The pyro-fuel was investigated via solid yield, high heating value HHV (proximate and ultimate analysis), fuel ratio, and atomic ratio, it was compared with the raw material WOS. As a result, the best pyro-fuel was ((pyro@90–650 reached HHV16.20 MJ/kg) and (pyro@120–650 reached HHV 15.95 MJ/kg)). The best HHV was increased from 9.11 to 16.20 MJ/kg enhanced by 77.82%, and the fuel ratio reached 0.77 of WOS, increased to 0.85 about a 10.40% increase of best pyro-fuel. While the atomic ratio was decreased of pyrochars, this indicated that the pyro-fuel was enhanced. As finding the pyro-fuel produced from WOS has a higher HHV and carbon content, which can be used as a solid carbon alternative fuel for energy production in the oil industry at NRC Baji.

Blending Saccharum bagasse and waste cooking oil for biofuel production via microwave co-torrefaction process

An efficient technology for producing renewable energy is urgently being developed due to the limited non-renewable resources, while disposing of biowaste and achieving zero-waste generation. To achieve the goals, this work explored the yielding of biochar as renewable energy by simultaneously recycling Saccharum bagasse (SB) and waste cooking oil (WCO) via microwave co-torrefaction (MCT). Influencing factors, including different torrefaction temperature (200–300 °C), reaction time (10–30 min), and WCO blending ratios (0%–15%), were systematically assessed using the box-behnken design (BBD) method. Results showed that the reaction temperature had a dominant impact on the biochar of higher-heating-value (HHV), followed by the WCO blending ratio. The HHV of the optimal biochar (24.7 MJ/kg), produced through MCT of SB at 300 °C for 26 min and blended with 15% WCO, was only marginally higher by 0.9% than the second highest HHV of the B12 biochar (24.5 MJ/kg), produced through MCT of SB at 300 °C for 20 min and blended with 15% WCO. Therefore, the B12 biochar was selected as the best condition in terms of energy efficiency. The B12 biochar exhibited superior energy density of 1.5, energy yield of 98.0%, fixed carbon content (17.5%), and thermal stability compared with the raw SB. The O/C and H/C ratios of the B12 biofuel were proximate to those of lignite. In contrast to bituminous coal, a 76.7% lower greenhouse gas (GHG) emissions and a satisfactory energy return on investment (EROI = 6.3) were achieved for the B12 biochar. Overall, the MCT of SB and WCO has a high potential in practical application for producing biochar with high HHV and energy density, good thermal stability, superior EROI, and low GHG emissions for providing green and renewable energy.

Physical and energetic characteristics of pellets produced from Movingui sawdust, corn spathes, and coconut shells

This study aims to perform a physical and energetic characteristics investigation of pellets produced from agricultural and forest biomass. Caloric Value, unit density, bulk density, volatile matter, ash contents, and fixed carbon content were evaluated according to international standards. Biomass pellets (10S30M60C) had the highest fixed carbon content (i.e., 25.52 ± 1.91%) and the highest HHV (i.e., 24,984.60 kJ/kg). The Movingui wood pellets had the highest volatile matter content (71.18 ± 0.57%). The highest ash content was observed in corn spathes pellets (7.07 ± 0.92%) and sawdust pellets had the lowest ash content (3.91 ± 0.36%). Thermogravimetric analysis shows that the pellets from the mixtures degrade over a large temperature range (about 220–540 °C); hence, the pellets from the mixtures of residues are more resistant thermally than the pellets from the unmixed residues. The pellets produced are eligible for industrial application according to their characteristics.

Valorizing manure waste into green coal-like hydrochar: Parameters study, physicochemical characteristics, combustion behaviors and kinetics

This work proposed an effective route from cow manure to coal-like hydrochar via hydrothermal carbonization (HTC). The effects of reaction conditions on product yields, physicochemical characteristics, and combustion performance of hydrochar were investigated. Both the increase of reaction temperature and reaction time resulted in the decrease of hydrochar yield but the increase of hydrochar quality, due to the strong dehydration and decarboxylation reactions occurring during HTC process. Particularly, HC-300-60 with a high HHV at 23.61 MJ/kg and high fuel ratio at 1.02, exhibited the comparable fuel quality with bituminous coal. Additionally, combustion behaviors and kinetics of hydrochars were tested by TG-DSC analysis. The hydrochar combustion process was more stable and moderate, with the minimum S index of 1.96 × 10−7%2/(°C3·min2) and the high activation energy of 50.40 kJ/mol. Simply put, this study indicates a green and promising route to valorize cow manure into high-quality solid fuel.

Effect of Ni, Mo and W on hydrothermal co-liquefaction of macroalgae and microalgae: Impact on bio-crude yield and composition

The co-hydrothermal liquefaction of macroalgae (Enteromorpha Clathrata) and microalgae (Chlorella Vulgaris) with metal catalyst was conducted at the temperature of 350 °C. Ni/MCM-41, Mo/MCM-41 and W/MCM-41 catalysts were used to investigate the role of catalyst on the bio-oil yield and composition distribution during hydrothermal liquefaction. the physicochemical properties of MCM-41, Ni/MCM-41, Mo/MCM-41, and W/MCM-41 were investigated by SEM, XRD, XPS, and NH3-TPD. These catalysts all reduced the production of bio-oil but improved the quality of bio-oil. The results of ultimate analysis showed that Ni/MCM-41 revealed high performance in hydrodeoxygenation and upgrading of bio-oil, and had the highest HHV. Mo/MCM-41 displayed an achievement in increasing the content of hydrocarbons (23.04%) and reducing the relative content of acid products in bio-oil. The W/MCM-41 had the most obvious effect on increasing the content of ester compounds and reducing the content of N-containing compounds in bio-oil.

Feasibility of thermal disposal masks in domestic waste incinerators: a study on the combustion characteristics, gaseous pollutant emissions characteristics and control of masks

ABSTRACT Discarded disposable medical masks generated due to the COVID−19 epidemic are overwhelming the current medical waste disposal facilities. Thermal disposal masks in domestic waste incinerator can both utilize the heat energy released by their combustion and dispose of the headache-inducing masks in a harmless manner. The masks are divided into 6 parts: white inside (WI), filter (FI), blue outside (BO), bonding of 3 parts (BP), ear strap (ES) and nose wire (NW). The highest burnout temperature (Tb) of each part of the mask was only 481.2°C and had a high HHV of 40.47 MJ/kg, which has a high energy potential as an energy source. The NOx, SO2, and HCl emission characteristics of each part of the masks were evaluated in a fixed-bed reactor. BP, BO, and ES contradict SO2 and HCl emission limits in China. The SO2 and HCl emission peaks of the masks with the addition of 10 wt% Ca(OH)2 did not exceed 60 mg/m3, which made the combustion emissions of the masks comply with GB 18,485–2014. Considering subsidies for disposal of masks and power generation, blending masks with a 1%−5% ratio enhances the subsidy revenue of waste incineration power plants by 12.63%−63.13%.

Strategies towards thermochemical valorisation of spent coffee grounds (SCG): Kinetic analysis of the thermal and thermo-oxidative decomposition

The thermochemical conversion of spent coffee grounds (SCG) under inert and oxidative conditions was comprehensively evaluated as a feasible valorisation route for this biomass. Dynamic thermogravimetric assays were carried out at different heating rates, where the individual contribution of the pseudo-components (hemicellulose, cellulose, lignin) was assessed by a deconvolution approach with Lorentz curves. The kinetic triplet, constituted by the apparent activation energy (Ea), the pre-exponential factor (A) and the model of reaction (g(a)), was defined for each pseudo-component through the application of iso-conversional methods, Master-Curves and Perez-Maqueda criterion. Under an inert atmosphere, the devolatilization of humidity, decomposition of hemicellulose, cellulose and part of lignin, and finally the completion of lignin were identified, resulting in a remaining percentage of 20% of biochar. For hemicellulose, Ea was 217 kJ mol−1, for cellulose 214 kJ mol−1, and lignin 151 kJ mol−1. Under oxidative conditions, analogous mass-loss stages were found, with the only difference being that biochar was decomposed until only ash (∼2%) was obtained as residue. The advantage of using SCG as biofuels, with a high LHV and HHV (∼20 MJ kg−1), was thus demonstrated. The Ea for the hemicellulose was 194 kJ mol−1, for cellulose 147 kJ mol−1, and for lignin was 173 kJ mol−1. Similar decomposition paths were found regardless of the atmosphere for hemicellulose (F4), hemicellulose (D3), and lignin (F2/4), which suggests that the temperature, the reactant concentration, the particle shape and the diffusion of products control the decomposition of SCG during non-isothermal pyrolytic or combustive thermochemical processes.

Role of levulinic acid in catalytic wet torrefaction of oil palm trunks: Insights into the hydrochar physicochemical properties, liquid phase composition, and reaction mechanisms

This study evaluates the effects of levulinic acid addition and different operating conditions on the physicochemical and structural properties of the resultant OPT hydrochar as well as on the liquid phase composition to identify its potential reaction pathway during wet torrefaction. The addition of levulinic acid enhances the solid yield and HHV of the hydrochar and promote repolymerisation and condensation reactions for the formation of secondary char with high HHV. The highest energy yield of 66.47% was attained from the OPT hydrochar wet torrefied at 220 °C for 24 h with 1.0 M of levulinic acid. Increasing the levulinic acid concentration promoted secondary chars to agglomerate. Liquid phase analyses showed that wet torrefaction of OPT in the presence of levulinic acid promotes the hydrolysis of hemicellulose and cellulose to glucose at mild operating conditions and enhances the rehydration of 5-HMF to levulinic acid.

Value-added biochar production from microwave pyrolysis of peanut shell

Abstract In order to seek efficient resource utilization, the carbonization of agricultural and forestry wastes through microwave pyrolysis technology is an important research hotspot to develop value-added products. The main objective is to produce value-added biochar through microwave pyrolysis of peanut shell in this study. The product yields, functional groups, and biochar HHVs caused by pyrolysis temperature (400, 450, 500, 550, and 600 °C), microwave power (350, 450, 550, 650, and 750 W), and residence time (10, 20, 30, 40, and 50 min) were investigated, and the energy recovery efficiencies were evaluated. It was obtained that the biochar yield declined monotonously within the range of 45.3–86.0 wt% with the enhancement of pyrolysis temperature, microwave power, or residence time. The pyrolysis temperature of 400 °C, microwave power of 350 W, and residence time of 10 min generated the maximum biochar yield (86.0 wt%). The value-added biochar was obtained with high HHV (20.15–31.02 MJ/kg) and abundant oxygen-contained functional groups (C–O bonds and C=O bonds). The maximum energy recovery efficiency during the whole process reached 97.96%. The results indicated that the peanut shell could reach high biochar yield through microwave pyrolysis, and potentially be transformed into value-added products with high energy recovery efficiency.

Feedstock and pyrolysis conditions affect suitability of biochar for various sustainable energy and environmental applications

Currently, the substitution of continuously depleting coal, a predominant source of global energy, and the treatment of contaminated soil and water bodies with sustainable means are the major concerns. Accordingly, biochars derived from slow pyrolysis of wood and rice residues (400–1000 °C) were observed to improve their properties over related feedstocks, among noticeable characteristic variations depending on the biomass type and pyrolysis temperature. Low-temperature pyrolysis produced high-yield biochars, and high-temperature pyrolysis produced low-yield, higher-C, and higher-HHV biochars. Wood residue biochars had higher HHV (21.25–24.05 MJ/kg) and lower H/C and O/C atomic ratios (0.643–0.201 and 0.326–0.084) than rice residue biochars (16.61–18.60 MJ/kg) and (1.22–0.259 and 0.720–0.558), respectively. Thus wood residue biochar, because of its substantially higher HHV than the threshold for an adequate solid fuel, have the potential for energy applications. The wood residue biochars (600–1000 °C) have higher C (>85%) than expected for pulverized coal injection (PCI, 75%C); and for coke, coke breeze, and recarburiser (85%C), together with much less ash and S content than required for blast furnace (BF). It can be utilized as PCI in BF (100%); as sintering solid fuel and BF nut-coke (50–100%); as BF carbon/ore briquette and steelmaking recarburiser (0–100%); and as a coal blend (2–10%) for coke-making, together with reduced onsite emissions. Wood residue biochars from 400 °C have the characteristic potential to replace 22.8% PCI and as a blend with lignite in existing coal-fired power plants. Wood residue biochars (600–1000 °C), with less H/C and O/C atomic ratios and a similar polarity index to pulverized fuel combustion coal, can be well applied in power-generating systems. Rice residue biochars (400–1000 °C), with poor persistence (O/Corg ratio, 1.228–0.799), higher alkali and alkaline earth metals content, and less HHV than the threshold for an adequate solid fuel, have weak prudence for fuel applications. But with other adaptable properties viz., higher pH, ash, (O/C and N/C) atomic ratios, polarity index, surface functional groups, plant nutrients, and moderate surface areas, can be selectively and judiciously utilized for soil amendment, soil-remediation, C-sequestration, wastewater treatment, and other pollutant abatements. Decision tree approaches, based on the characteristic pertinence of these biochars with literature values, have been developed for their various sustainable energy and environmental usages; and associated environmental concerns and needs to promote them to industrial-level applications have been discussed.

Effects of oxidative torrefaction on the physicochemical properties and pyrolysis products of hemicellulose in bamboo processing residues

Torrefaction pretreatment is applied to improve the fuel quality of biomass. However, in industrial production, oxygen can be unintentionally involved in the torrefaction process due to insufficient airtightness of the torrefaction reaction equipment or the presence of voids in the biomass particles. In this study, hemicellulose was extracted from the bamboo processing residue and was used as raw material for torrefaction experiment. We mainly studied the effects of oxidative torrefaction on physical and chemical properties of torrefied hemicellulose and the distribution of pyrolysis products under different oxygen concentrations and torrefaction temperatures. Results showed that a lower torrefaction temperature (200 °C) yielded solid products with higher HHV even when the oxygen concentration was increased to 15%. With a 5% oxygen concentration, a higher torrefaction temperature can apparently reduce the oxygen and hydrogen contents, and decrease atomic O/C and H/C ratios in torrefied hemicellulose. In terms of the pyrolysis products, at torrefaction temperature of 230 °C and 5% oxygen concentration, pyrolysis products had the lowest acid (7.85%) and the highest ester (6.32%) contents, indicating the highest quality of chemical compounds. A higher oxygen concentration of 5% was beneficial for the formation of alcohols in pyrolysis products. The highest content of furans (34.75%) in the pyrolysis products was achieved after torrefaction pretreatment at 260 °C and 5% oxygen concentration. The production of phenolics compounds favored lower temperature of 200 °C and 0% oxygen concentration in torrefaction pretreatment. This work provides a new avenue to improve the quality of pyrolysis products of biomass through oxidative torrefaction. Effects of oxidative torrefaction on the physicochemical properties and pyrolysis products distributions of hemicellulose derived from bamboo processing residues. • Effects of oxidative torrefaction on hemicellulose properties were investigated. • Hemicellulose underwent dehydrogenation, and deoxygenation, and less extent decarbonization during torrefaction. • Torrefaction pretreatment of hemicellulose at 230 °C and 5% oxygen concentration favored high-value pyrolysis products.

A comparison of char fuel properties derived from dry and wet torrefaction of oil palm leaf and its techno-economic feasibility

In this study, the chars were derived through dry and wet torrefaction (DT and WT) of oil palm leaf (OPL), and techno-economic feasibility for char production was evaluated. DT was performed at 200 to 300 °C for 30 min under CO2 atmosphere. WT was performed at 180 to 220 °C for 30 min over process water (PW) reuse. Fuel properties of the DT-char and WT-char products, including mass yield, physiochemical characteristics, fuel properties, thermal stability, surface chemical functional groups, and surface structure were investigated. The study results indicated that DT affected OPL characteristics rather than WT, where the char with outstanding fuel properties was derived through DT. WT affected the fuel properties of OPL marginally. OPL chars with the highest HHV (28.67 MJ/kg), HHV improvement (0.48) and energy yield (131.78 %) could be derived via the DT. The O/C and H/C ratios of the DT-char were reduced and similar to those of lignite coal. PW reuse in WT slightly affected the char fuel properties, thus it is the outstanding method of PW utilization. Techno-economic feasibility analysis results determined that DT is the profitable process for converting OPL to char fuel, and its simple payback period is 14.13 years. These results recommended that DT constitutes a dominant technology for producing char fuel from OPL.

Effects of biological pre-digestion of sewage sludge processed by fast pyrolysis on bio-oil yield and biochar toxicity

Studies on the evaluation of sewage sludge (SS) as a feedstock through thermochemical processes have gained momentum. Due to the complex structure of SS, it is necessary to determine SS treatment stage to which thermochemical processes will be added to the wastewater treatment plants and to configure the optimum process scheme. The pyrolysis process is an important process for resource recovery as bio-oil and biochar. While bio-oil is important source of the value-added products, biochar is widely evaluated as soil improver. With the aim of the designation of the optimum process scheme for pyrolysis of three different sewage sludges (SSs): raw SS (RSS), anaerobically digested SS (ANSS), and aerobically digested SS (AESS); after the investigation of thermal behaviors by thermogravimetric analysis (TGA), the optimum process conditions were investigated to obtain maximum possible bio-oil yield from fast pyrolysis of SSs. By applying the central composite design in the response surface methodology, optimum fast pyrolysis operating conditions were determined for each SS type and the fast pyrolysis products obtained under optimum conditions were characterized. While the highest HHV was achieved for RSS, lowest activation energy (Ea) and maximum bio-oil yield was achieved for AESS. The optimum fast pyrolysis operating conditions for obtaining maximum bio-oil yield as 35.75 % were determined as 485 °C and 100 mL min−1 carrier gas flowrate for AESS. While the bio-oil produced from ANSS was determined as a resource for oleic acid production, the toxicity test results revealed that biochar produced from fast pyrolysis of AESS is suitable for soil amendment.

Study on preparation of aromatic-rich oil by thermal dechlorination and fast pyrolysis of PVC

Thermal dechlorination and fast pyrolysis experiments of PVC were carried out. Characterizations such as TG, FTIR and 13C NMR were applied to analyze the thermal degradation characteristics and chemical structure evolution characteristics of de-HCl PVC during the dechlorination process. The thermal dechlorination results show that the degree of dechlorination and aromatization of de-HCl PVC is deepened with the increasing dechlorination temperature. The dechlorination efficiency is as high as 99.86% at 320 ℃. Meanwhile, the de-HCl PVC with a chlorine content of 0.22% and the optimal H/Ceff value for aromatics production can be obtained. The de-HCl PVC gradually evolves from a long chain structure with C-C bonds as the skeleton to a long olefin chain structure with partial aromatization during the dechlorination process. The fast pyrolysis results show that the oil generated by the de-HCl PVC (320 °C) pyrolysis has a high aromatic content of 97.32%−99.93%. In addition, there are no chlorine-containing compounds in the oil from de-HCl PVC (320 °C) pyrolysis, while the PVC pyrolysis oil contains chlorinated aromatics with high content of 1.91%−4.02%. During the fast pyrolysis process, the monocyclic aromatic hydrocarbons (MAHs) are mainly formed from the cyclization of polyene fragments released by random fragmentation of de-HCl PVC (320 ℃). Further, the polycondensation reaction is promoted to realize the conversion of MAHs to polycyclic aromatic hydrocarbons (PAHs) under the action of high temperature. The by-products of pyrolysis gas with high HHV and carbon-rich char both can be further utilized. Overall, thermal dechlorination and fast pyrolysis can realize harmless treatment and high-value utilization of PVC.

Conversion of sewage sludge from industrial wastewater treatment to solid fuel through hydrothermal carbonization process

Sludge is the unwanted solid waste produced during the treatment of industrial wastewater. The hydrothermal carbonization process (HTC) can be used to convert sewage sludge into a coal-like solid fuel. The effects of solid-to-liquid ratio and feed water pH on the physicochemical properties of hydrochars were investigated. According to the results, hydrothermal treatment enhanced the fuel characteristics of hydrochar with a high HHV and fixed carbon. Adding 0.8 M acetic acid resulted in the highest rate of energy recovery at 96.98 %. The observed H/C and O/C atomic ratios of HTC-0.4AA have been lowered to levels comparable to lignite coal. ICP-OES confirmed the presence of the metal in the hydrochar product. Examining the thermogravity analysis of raw materials and hydrochars with a TGA analyzer was then used to determine the combustion kinetics. In addition, combustion characteristics indicate that HTC improves the S combustibility index.

Bimetallic Lanthanum-Cerium-Loaded HZSM-5 Composite for Catalytic Deoxygenation of Microalgae-Hydrolyzed Oil into Green Hydrocarbon Fuels.

Due to their high lipid content, microalgae are one of the most significant sources of green hydrocarbons, which might help lessen the world's need for fossil fuels. Many zeolite-based catalysts are quickly deactivated by coke production and have a short lifetime. In this study, a bimetallic Lanthanum-Cerium (La-Ce)-modified HZSM-5 zeolite catalyst was synthesized through an impregnation method and was tested for the conversion of hydrolyzed oil into oxygen-free hydrocarbon fuels of high energy content. Initially, hydrolyzed oil (HO), the byproduct of the transesterification process, was obtained by the reaction of crude oil derived from Chlorella vulgaris microalgae and a methanol. Various catalysts were produced, screened, and evaluated for their ability to convert algal HO into hydrocarbons and other valuable compounds in a batch reactor. The performance of HZSM-5 was systematically tested in view of La-Ce loaded on conversion, yield, and selectivity. NH3-TPD analysis showed that the total acidity of the La-Ce-modified zeolites was lower than that of the pure HZSM-5 catalyst. TGA testing revealed that including the rare earth elements La and Ce in the HZSM-5 catalyst lowered the catalyst propensity for producing coke deposits. The acid sites necessary for algal HO conversion were improved by putting La and Ce into HZSM-5 zeolite at various loading percentages. The maximum hydrocarbon yield (42.963%), the highest HHV (34.362 MJ/Kg), and the highest DOD% (62.191%) were all achieved by the (7.5%La-2.5%Ce)/HZSM-5 catalyst, which was synthesized in this work. For comparison, the hydrocarbon yield for the parent HZSM-5 was 21.838%, the HHV was (33.230 MJ/Kg), and the DOD% was 44.235%. In conclusion, La and Ce-loading on the parent HZSM-5 may be responsible for the observed alterations in textural properties; nevertheless, there is no clear correlation between the physical features and the hydrocarbon yield (%). The principal effect of La and Ce modifying the parent HZSM-5 zeolite was to modify the acidic sites needed to enhance the conversion (%) of the algal HO during the catalytic deoxygenation process, which in turn raised the hydrocarbon yield (%) and increased the HHV and DOD%.

Luffa cylindrica Slow Pyrolysis and Solar Pyrolysis: Impact of Temperature and Heating Rate on Biochar Properties and Iodine Adsorption Performance

Recently, Luffa cylindrica has been drawing lots of attention in adsorption applications. However, the contaminated biomass needs to be properly disposed. Pyrolysis is a process capable of turning this type of residue into valuable product. Luffa cylindrica pyrolysis produces biochar which has been used as adsorbent for various cationic and organic species. Additionally, the use of solar power to heat the reactor reduces the environmental impact of pyrolysis. In this work, a lab-scale solar pyrolizer was built in a 40-dollar budget. This biomass was previously subjected to slow pyrolysis in an electrical reactor at various temperatures (300, 400, and 500 °C) and heating rates (2, 10, and 20 °C min−1) to assess the influence of these parameters on biochar properties. Further, the Luffa sponge sample was subjected to solar pyrolysis. The characterization methods of TG/DTG, FTIR, SEM, and HHV analysis were employed to assess biochar properties. Biochar adsorption performance was assessed by iodine adsorption experiments. Highest HHV (29.3 MJ kg−1) was obtained for the biochar from the 500 °C, 2 °C min−1 pyrolysis. Maximum iodine adsorption (162.9 mg g−1) was observed on the biochar produced at 400 °C, 2 °C min−1. Solar biochar had a 24.3 MJ kg−1 HHV and a Iodine adsorption of 115.2 mg g−1.Graphical Abstract