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The CaO/Ca(OH)2 system can be the basis for cost-efficient long-term energy storage, as the chemically stored energy is not affected by heat losses, and the raw material is cheap and abundantly available. While the hydration (thermal discharge) has already been addressed by several studies, for the dehydration (thermal charge) at low partial steam pressures, there is a lack of numerical studies validated at different conditions and operation modes. However, the operation at low steam pressures is important, as it decreases the dehydration temperature, which can enable the use of waste heat. Even if higher charging temperatures are available, for example by incorporating electrical energy, the reaction rate can be increased by lowering the steam pressure. At low pressures and temperatures, the limiting steps in a reactor might change compared to previous studies. In particular, the reaction kinetics might become limiting due to a decreased reaction rate at lower temperatures, or the reduced steam density at low pressures could result in high velocities, causing a gas transport limitation. Therefore, we conducted new measurements with a thermogravimetric analyzer only for the specific steam partial pressure range between 0.8 and 5.5 kPa. Based on these measurements, we derived a new mathematical fit for the reaction rate for the temperature range between 375 and 440 °C. Additionally, we performed experiments in an indirectly heated fixed bed reactor with two different operation modes in a pressure range between 2.8 and 4.8 kPa and set up a numerical model. The numerical results show that the model appropriately describes the reactor behavior and is validated within the measurement uncertainty. Moreover, our study revealed an important impact of the operation condition itself: the permeability of the reactive bulk is significantly increased if the dehydration is initiated by a rapid pressure reduction compared to an isobaric dehydration by a temperature increase. We conclude that the pressure reduction leads to structural changes in the bulk, such as channeling, which enhances the gas transport. This finding could reduce the complexity of future reactor designs. Finally, the presented model can assist the design of thermochemical reactors in the validated pressure and temperature range.

Hydrogen gas is an ideal fuel due to its higher calorific value among fuels and minimal environmental impact on their energy applications. However, the high cost around high reactivity, explosion risks and extremely low energy density, make it unfeasible to be used as fuel in large quantities scale. There are some possibilities to circumvent these limitations, including obtaining and converting energy through fuel cells, which is very promising. Research in this field has been summarized in recent decades, motivated by the environmental problems faced due to the dependence on non-renewable energy matrices. From this, this study aimed to improve the steam methanol reforming using CuO/ZnO/Al2O3 catalyst. The catalyst was characterized by atomic absorption spectroscopy, N2 physisorption and XRD. Catalytic tests were carried out in a laboratory scale fixed bed reactor at 300°C, atmospheric pressure and in differential conditions (methanol conversion < 10%); a previous run for catalyst synthesis validation in relation to the results obtained in the literature for the same conditions was evaluated. Subsequently, it was found that the thermal degradation of methanol at 300°C without the presence of the catalyst was negligible, and then operational conditions were established to obtain methanol conversions lower than 10%. Then, the initial deactivation of the catalyst over 31h. Also identifying the stability after 7 h in reaction with average conversion into 9.7% of methanol, showing high stability, in addition to good reproducibility on the part of synthesis in optimal composition. Then, experiments were carried out for the molar ratios 2:1 and 4:1 with methanol conversions of 15.5% and 6.6%, respectively. Note that performing the average of the 4:1 and 2:1 methanol conversion in 14.6% obtained at indicating that the upper boundary molar ratios (4:1) compensates for the conversion reduction in 2:1, achieving a result superior to the reference 3:1.

Currently, most plastic waste stems from packaging materials, with a large proportion of this waste either discarded by incineration or used to derive fuel. Accordingly, there is growing interest in the use of pyrolysis to chemically recycle non-recyclable (i.e., via mechanical means) plastic waste into petrochemical feedstock. This comparative study compared pyrolysis characteristics of two types of reactors, namely fixed and fluidized bed reactors. Kinetic analysis for pyrolysis of SRF was also performed. Based on the kinetic analysis of the pyrolytic reactions using differential and integral methods applied to the TGA results, it was seen that the activation energy was lower in the initial stage of pyrolysis. This trend can be mainly attributed to the initial decomposition of PP components, which was subsequently followed by the decomposition of PE. From the kinetic analysis, the activation energy corresponding to the rate of pyrolysis reaction conversion was obtained. In conclusion, pyrolysis carried out using the fluidized bed reactor resulted in a more active decomposition of SRF. The relatively superior performance of this reactor can be attributed to the increased mass and heat transfer effects caused by fluidizing gases, which result in greater gas yields. Regarding the characteristics of liquid products generated during pyrolysis, it was seen that the hydrogen content in the liquid products obtained from the fluidized bed reactor decreased, leading to the formation of oils with higher molecular weights and higher C/H ratios, because the pyrolysis of SRF in the fluidized bed reactor progressed more rapidly than that in the fixed bed reactor.

Renewable hydrogen production by aqueous phase reforming (APR) over Ni/Al-Ca catalysts was studied using pure or refined crude glycerol as feedstock. The APR was carried out in a fixed bed reactor at 238 °C, 37 absolute bar for 3 h, using a solution of 5 wt.% of glycerol, obtaining gas and liquid products. The catalysts were prepared by the co-precipitation method, calcined at different temperatures, and characterized before and after their use by several techniques (XRD, ICP-OES, H2-TPR, NH3-TPD, CO2-TPD, FESEM, and N2-physisorption). Increasing the calcination temperature and adding Ca decreased the surface area from 256 to 188 m2/g, and its value after the APR changed depending on the feedstock used. The properties of the acid and basic sites of the catalysts influenced the H2 yield also depending on the feed used. The Ni crystallite was between 6 and 20 nm. In general, the incorporation of Ca into Ni-based catalysts and the increase of the calcination temperature improved H2 production, obtaining 188 mg H2/mol C fed during the APR of refined crude glycerol over Ni/AlCa-675 catalyst, which was calcined at 675 °C. This is a promising result from the point of view of enhancing the economic viability of biodiesel.

Acid-modified red mud supported by peanut shells (MRP) catalysts were prepared for the catalytic wet persulfate oxidation (CWPO) process of dyes wastewater (containing methyl orange (MO), NH3-N, and Cr6+) in batch and continuous fixed bed reactors. Importantly, the influence of NH3-N and Cr6+ on the catalytic performance of the MRP catalyst was primarily studied. In the CWPO process, the reactors had a remarkable degradation efficiency (72–97%) of MO in the dyes wastewater. In the batch reactor, with the increase of NH3-N concentration (5–20 mg L−1), the degradation efficiency of MO was maintained at 93%. When NH3-N, Cr6+, and MO coexist, the degradation of MO had slight inhibition with 87.24%, which indicated that MO concentration was still controlled by MRP under the coexistence system, and the order of the removal effect of MRP on the three pollutants in the reactors was as follows: MO > NH3-N > Cr6+. Furthermore, in the fixed reactor, with the increasing of NH3-N or Cr6+ concentration, the MO degradation removal decreased to about 84%. The results showed that the degradation effect of MO in a fixed bed is still considerable. Then, the SEM and FTIR results indicated that SO4·−, ·OH, and O2−· generated in the CWPO process and Fe2+ and oxygen-containing functional groups on MRP played a major role on the degradation of pollutants. This study showed that this novel MRP is a promising catalyst with promising applications in composite dyes wastewater.

Catalytic upgrading of vapors from pyrolysis of triglycerides materials is a promising approach to achieve better conversions of hydrocarbons and production of liquid biofuels. Catalytic cracking often shows incomplete conversion due to distillation of initial reaction products and the addition of a second catalytic reactor, whereas pyrolytic vapors are made in contact to a solid catalyst was applied to improve the physical-chemical properties and quality of bio-oil. This work investigated the effect of catalyst content and reaction time by catalytic upgrading from pyrolysis vapors of residual fat at 450 °C and 1.0 atmosphere, on the yields of reaction products, physicochemical properties (density, kinematic viscosity, refractive index, and acid value), and chemical composition of organic liquid products (OLP), over a catalyst fixed bed reactor, in semi pilot scale. Pellets of red mud chemically activated with 1.0 M HCl were used as catalysts. The thermal catalytic cracking of residual fat show OLP yields from 54.4 to 84.88 (wt.%), aqueous phase yields between 2.21 and 2.80 (wt.%), solid phase yields (coke) between 1.30 and 8.60 (wt.%), and gas yields from 11.61 to 34.22 (wt.%). The yields of OLP increases with catalyst content while those of aqueous, gaseous and solid phase decreases. For all experiments, the density, kinematic viscosity, and acid value of OLP decreases with reaction time. The GC-MS of liquid reaction products identified the presence of hydrocarbons and oxygenates. In addition, the hydrocarbon content in OLP increases with reaction time, while those of oxygenates decrease, reaching concentrations of hydrocarbons up to 95.35% (area.). The best results for the physicochemical properties and the maximum hydrocarbon content in OLP were obtained at 450 °C and 1.0 atmosphere, using a catalyst fixed bed reactor, with 5.0% (wt.) red mud pellets activated with 1.0 M HCl as catalyst.

Enzymatic degradation of emerging contaminants has gained great interest for the past few years. However, free enzyme often incurs high costs in practice. The immobilized laccase on the polyethylenimine (PEI)‐functionalized magnetic nanoparticles (Fe3O4–NH2–PEI–laccase) was fabricated to efficiently degrade phenolic compounds continuously in a newly fixed bed reactor under a high‐gradient magnetic field. The degradation rate of continuous treatment in the bed after 18 h was 2.38 times as high as that of batch treatment after six successive operations with the same treatment duration. Under the optimal conditions of volume fraction of nickel wires mesh, flow rate of phenol solution, phenol concentration, and Fe3O4–NH2–PEI–laccase amount, the degradation rate of phenol kept over 70.30% in 48 h continuous treatment. The fixed bed reactor filled with Fe3O4–NH2–PEI–laccase provided a promising avenue for the continuous biodegradation of phenolic compounds for industrial wastewater in practice.

Fe-impregnated 13X (Fe-13X) catalysts were prepared for catalytic wet peroxide oxidation (CWPO) of methyl orange (MO) solution in batch and continuous fixed bed reactors. A systematical study was carried out to investigate the influence of the main operating parameters on the batch reactor performance. The kinetic curves were analyzed by using a pseudo-first-order kinetic equation over the 30–70 °C temperature range. In addition, the effects of catalysts filling amount and feed flow rate on the catalytic performance of Fe-13X catalysts in a fixed bed reactor were studied. The experimental results showed that the Fe-13X catalysts achieved the highest activity (100% MO conversion and 74.5% chemical oxygen demand (COD) elimination ratio, respectively) at 25 min with trace mount of Fe leaching concentration (<2.1 mg/L) at the optimized reaction conditions (namely 1.0 g/L catalyst concentration, pH 2.0, 17.6 mM H2O2, 70 °C) in a batch reactor. Kinetic studies showed that two different reaction regions existed, and an activation energy of 51.9 kJ/mol for the second region was found. Under the optimal operating conditions found (namely, catalysts filling amount of 3.5 g, feed flow rate of 4 mL/min), the Fe-13X catalysts displayed high MO conversion (99.4%) and COD elimination ratio (77.1%) after continuously ran for 200 min in a fixed bed reactor.

C ommercial cylindrical mesoporous silica pellets (3 mm diameter by 3–6 mm length) were modified by coring the pellets and inserting a 1 mm diameter copper wire along the long axis of the pellet, to give a pseudo core–shell support. While there were negligible differences in the thermal conductance of the two supports, the volumetric thermal capacitance of the core–shell support was 4.1 times greater than the unmodified silica. Fischer–Tropsch synthesis (FTS) catalysts comprised of 16 wt% Co and 1.5 wt% Ru immobilized on the native pellets (control catalyst, CT) or on the core–shell support (CS-Cu catalyst) were prepared, placed in a tubular packed-bed reactor and reduced with H 2 at 400 °C. The catalysts were conditioned for FTS (255 °C; 10 atm; H 2 /CO = 2; GSV 510 h −1 ) by cooling to 150 °C, changing to a syngas atmosphere, and slowly ramping to the run temperature of 255 °C over 8 h. Measurements of the catalyst bed temperature and furnace temperature during the activation and run time revealed frequent and large temperature spikes (∆T ~ 70 °C) in the CT bed, especially in the first 12 h of operation. In comparison, runs using the CS-Cu catalyst experienced fewer and less substantive temperature spikes (∆T ~ 30 °C). From the thermal data and the FTS productivity data, it was clear that the CT catalyst experienced a substantially greater degree to deactivation due to the thermal spikes than the CS-Cu catalysts. At similar conversions, the CS-Cu showed 50% greater productivity (g product /g Co – h) and a small but reproducible improvement in C 5+ selectivity (52–55 wt%). Notably, the CS-Cu catalyst gave an appreciably smaller amount of the olefinic product (3 vs 15%). The thermal capacitance of the CS-Cu clearly moderates the negative consequences of local exotherms in the catalyst bed, especially during the activation phase of the FTS run.

The primary aim of this study is to break down the methoxy (-OCH 3 ) and hydroxyl(-OH) oxygenates present in lignin, a component of biomass. This degradation was performed on a lignin-derived model compound, guaiacol, using a highly effective Ni-loaded SBA-15 catalyst. SBA-15 was synthesized via a hydrothermal method, and varying amounts of NiO (5, 10, 15, 20, 25 wt%) were incorporated into SBA-15 through wet impregnation. The catalysts were characterized by using techniques such as XRD, DRS-UV, FT-IR, TPR, BET, SEM, and HR-TEM. Their catalytic performance was evaluated through the hydrodeoxygenation of guaiacol in a vapor phase reactor under controlled atmospheric pressure conditions. Notably, at 200 °C with a hydrogen flow rate of 50 ml/h, the 10 wt% NiO/SBA-15 catalyst demonstrated superior catalytic activity, achieving high guaiacol conversion and aimed product selectivity.