Fixed-bed Reactor Research Articles

A quantitative investigation on pyrolysis behaviors of metal ion-exchanged coal macerals by interpretable machine learning algorithms

Generalizing the rules from complex processes such as catalytic pyrolysis to guide their process control is always a difficult but attractive task. The influences of ion-exchange of metal ions (Na+, K+, Ca2+, Mg2+, Co2+ and Ni2+) on the pyrolysis behavior of vitrinite and inertinite from Shendong coal were investigated by thermogravimetric analyzer-Fourier transform infrared spectrometer (TG-FTIR), fixed-bed reactor (FBR), gas chromatograph-mass spectrometer (GC-MS) and X-ray diffractometer (XRD). A set of machine learning models was successfully constructed based on random forest, support vector machine, and Gaussian process regression, to quantify the relationships between pyrolysis behaviors and the properties of metals and macerals. The leave-one-out-cross validation showed that there are considerable determination coefficients (R2 > 0.9) between predicted and experimental values for most responses (17 out of 29). By combining genetic programming-based symbolic regression with the black-box algorithm, 23 symbolic regression expressions with high confidence were successfully constructed. This work is a pioneering attempt of optimization in small-scale experiments. By utilizing the highly interpretable models, a demand-orientated (multi-)optimization coal pyrolysis can be achieved. The bi-objective optimization was conducted on the yield of tar and the content of light aromatics in tar, and the results show that Co is the optimal loading metal.

Enhancing biomass gasification: A comparative study of catalyst applications in updraft and modifiable-downdraft fixed bed reactors

This study aims to investigate the effects of different catalysts on biomass gasification. Therefore, red mud (RM) and Aluminum–Nickel alloy were used as catalysts with biomass mixture (BM) for the lab-scale gasification studies by using an updraft and a modifiable-downdraft fixed bed reactor. The maximum volumetric percentage of H2, ranging from 51% to 65%, was achieved at 900 °C in both gasifiers. Al–Ni catalyst significantly boosted H2 content, reaching 65% in the updraft gasifier at 900 °C with 0.05 L/min dry air. H2/CO ratio varied from 2 to 4 for BM, while catalyst use expanded the range to 1.6–7 with the Al–Ni catalyst demonstrating the most effective performance. In general, it was seen that RM increased the H2 component in the syngas between 1 and 7 vol% at 900 °C in updraft gasifier. In the modifiable-downdraft reactor, on the contrary, H2 concentration in the syngas decreased by 2–6% with the addition of RM.

Life Cycle Assessment of Wheat Straw Pyrolysis with Volatile Fractions Chemical Looping Combustion

Among the approaches to facilitating negative CO2 emissions is biochar production. Biochar is generated in the pyrolysis of certain biomasses. In the pyrolysis process, carbon in the biomass is turned into a solid, porous, carbon-rich, and stable material that can be captured from the soil after a period of from a few decades to several centuries. In addition to this long-term carbon sequestration role, biochar is also beneficial for soil performance as it helps to restore soil fertility and improves the retention and diffusion of water and nutrients. This work presents a Life Cycle Assessment of different pyrolysis approaches for biochar production. Biomass pyrolysis is performed in a fixed-bed reactor, which operates at a mild temperature (550 °C). Biochar is obtained as solid product of the pyrolysis, but there are also liquid (bio-oil) and gaseous products (syngas). The pyrolysis gas is partly used to fulfil the energy demand of the pyrolysis process, which is highly endothermic. In the conventional approach, CO2 is produced during the combustion of syngas and emitted to the atmosphere. Another approach to facilitate CO2 capture and thus obtain more negative CO2 emissions in the pyrolysis process is burning syngas and bio-oil in a Chemical Looping Combustion unit. Life Cycle Assessment was performed of these approaches toward biomass pyrolysis to evaluate their environmental impact. The Chemical Looping Combustion approach significantly reduced the values of 7 of the 16 environmental impact indicators studied, along with the Global Warming Potential among them, it slightly increased the value of one indicator related to the use of fossil resources, and it maintained the values of the remaining 8 indicators. Environmental impact reduction occurs due to the avoidance of CO2 and NOx emissions with Chemical Looping Combustion. The CO2 balances of the different pyrolysis approaches with Chemical Looping Combustion configurations were compared with a base case, which constituted the direct combustion of wheat straw to obtain thermal energy. Direct biomass combustion for the production of 17.1 MJ of thermal energy had CO2 positive emissions of 0.165 kg. If the gaseous fraction was burned by Chemical Looping Combustion, CO2 was captured and the emissions became increasingly negative, until a value of −3.30 kg/17.1 MJ was generated. If bio-oil was also burned by this technology, the negative trend of CO2 emissions continued, until they reached a value of −3.66 kg.

Study of Ni-Co-ZrO2/Al2O3 Catalysts for Carbon Dioxide Reforming of Methane at Low CO2

This work studied the composition of Ni-Co-ZrO2/Al2O3 catalyst on properties and efficiency of catalysts for carbon dioxide reforming of methane (CMR) when CO2 was fed as the limiting reagent and CH4 as the excess reactant. 9wt%Ni-1wt%ZrO2/Al2O3, 4.5wt%Ni-4.5%wtCo-1wt%ZrO2/Al2O3, 9wt%Co-1wt%ZrO2/Al2O3 and 7wt%Co-3wt%ZrO2/Al2O3 catalysts were prepared by wet impregnation method. The physicochemical properties of present catalysts were characterized by XRD, N2 adsorption-desorption H2-TPR and CO2-TPD. The CRM performance was determined in a tubular fixed-bed reactor at 600 °C for 6 h with limiting of carbon dioxide. The carbon deposition on spent catalysts were examined by TGA. The results showed that Co-ZrO2 catalysts provided greater activities, selectivity toward H2 and stability than Ni-ZrO2 and Ni-Co-ZrO2 catalysts. 9wt%Co-1wt%ZrO2/Al2O3 provided higher reactant conversions and H2/CO ratio than 7wt%Co-3wt%ZrO2/Al2O3 while the minimum coke formation was observed on spent 7wt%Co-3wt%ZrO2/Al2O3. It is because oxophilic properties and oxygen vacancy sites in Co-ZrO2 increase CO2 dissociative adsorption as well as oxygen transport on the catalyst surface. HIGHLIGHTS This work developed Ni-Co-ZrO2/Al2O3 catalysts for carbon dioxide reforming of methane (CMR) when CO2 is fed as the limiting reagent demonstrated petroleum refinery application. Remarkable points of this work are revealed below. Co-ZrO2 catalysts provided greater reactant activities, selectivity toward H2 and stability than Ni-ZrO2 and Ni-Co-ZrO2 The oxophilic property accompanied with oxygen vacancy sites in Co-ZrO2 increase CO2 dissociative absorption and oxygen transport on the catalyst surface. 9wt%Co-1wt%ZrO2/Al2O3 provided relative highest reactant conversions and highest H2/CO ratio. 7wt%Co-3wt%ZrO2/Al2O3 presented the minimum coke formation. GRAPHICAL ABSTRACT

Sorption-enhanced intensified CO2 hydrogenation via reverse water–gas shift reaction: Kinetics and modelling

Intensification of CO2 hydrogenation via the reverse water–gas shift (RWGS) reaction for CO production can be achieved through in situ removal of water when hydrophilic adsorbents are incorporated alongside the catalyst in the reaction bed. In this work, seeking to move a step closer to the industrial implementation of this innovative CO2 valorization process, a comprehensive reactor model, validated by experimental data obtained in a fixed-bed reactor, was developed to simulate the behavior of this sorption-enhanced (SE) RWGS process. Simulation and experimental data matched with good accuracy, demonstrating the striking benefits brought by the adsorbent addition, such as an almost doubling of the CO production rate at 300 °C. The kinetics of RWGS reaction over a Cu-based catalyst and H2O adsorption on a 13X zeolite adsorbent were studied both experimentally and theoretically and the kinetic models were integrated into the reactor model to assess the performance of SE-RWGS process. Fitting of the RWGS reaction rates by a Langmuir-Hinschelwood-Hougen-Watson-type heterogeneous kinetic model suggested that the rate-determining step of the reaction is the surface interaction between an adsorbed CO2 molecule and a H* species on catalytic sites of different nature. Meanwhile, the dynamic behavior of water adsorption was effectively simulated by a semi-empirical double-stretched exponential model combined with the Sips isotherm model. The results of this work could be applied to the design and scale-up of the SE-RWGS process, which offers considerable improvements over the thermodynamically constrained conventional process. The intensified approach represents a promising avenue for the effective conversion of carbon dioxide into CO, as well as into other value-added chemicals as part of a multi-stage CO2 reduction process.

Microwave-Assisted dry reforming of toluene as a model tar compound using low-cost iron catalyst for syngas clean-up

Gasification of waste feedstock such as biomass, waste plastics suffers from high tar yields during hydrogen-rich syngas production. The presence of tars result in lower quality syngas, lower syngas yields, reactor blockage, reactor down time, and costly maintenance. Therefore, removal of tar from syngas during gasification is essential. Catalytic reforming of tars via in-situ syngas cleanup is an effective way of mitigating tars. This work explores the possibility of microwave-assisted catalytic dry reforming of tars for syngas production. Due to its chemical complexity, toluene, which is one of the main tar constituents, could be used as a model tar compound. Toluene dry reforming was studied using the Fe/Al2O3 catalyst under CO2 under the temperature range of 400–700 ℃. The toluene reforming reaction was conducted using microwave and conventional thermal reactors. Under microwave irradiation, CO2 and toluene conversions are boosted to 80% at 500 ℃. Hydrogen and carbon monoxide yields were approximately five times and ten times higher in the microwave reactor at 500 ℃, respectively, compared to the productions obtained in the conventional fixed-bed reactor at 700 ℃. Filamentous carbon was also produced as a valuable side product to improve the economy of this process and such value-added carbon was only observed in the microwave reactor. Three reaction pathways were observed during microwave reaction: the toluene decomposition produces an initial hydrogen and carbon deposit on the catalyst; the formation of methane and benzene suggests toluene hydrodemethylation as a secondary reaction; and toluene hydrogenolysis forms light alkanes such as methane, and through reforming reaction under CO2 to syngas.

Effect of Feed Mass, Reactor Temperature, and Time on the Yield of Waste Polypropylene Pyrolysis Oil Produced via a Fixed-Bed Reactor.

This paper presents the results of investigations into the pyrolysis of waste polypropylene in a laboratory fixed-bed batch reactor. The experiments were designed and verified in such a way as to allow the application of the response surface methodology (RSM) in the development of an empirical mathematical model that quantifies the impacts mentioned above. The influence of the mass of the raw material (50, 100, and 150 g) together with the reactor temperature (450, 475, and 500 °C) and the reaction time (45, 50 and 75 min) was examined. It has been shown that the mass of the raw material, i.e., the filling volume of the reactor, has a significant influence on the pyrolysis oil yield. This influence exceeds the influence of reactor temperature and reaction time. This was explained by observing the temperature change inside the reactor at three different spots at the bottom, middle, and top of the reactor. The recorded temperature diagrams show that, with greater masses of feedstock, local overheating occurs in the middle part of the reactor, which leads to the overcracking of volatile products and, from there, to an increased formation of non-condensable gases, i.e., a reduced yield of pyrolytic oil.

In-situ synthesis of V2AlC@V2O5/TiO2 immobilized over honeycomb support with vanadium oxide electron transfer mediator for stimulating selective CO2 photoreduction through bi-reforming in a monolith reactor

Photocatalytic CO2 reduction to valuable chemicals and fuels is a practical approach for climate action; however, available photocatalysts and photoreactors are less efficient. In this work, well-designed V2AlC@V2O5 supported TiO2 and immobilized over honeycomb support for CO2 photoreduction in a monolith reactor have been investigated. The catalysts were loaded over the monolithic support using the sol-gel dip-coating method and found promising for higher light absorbance and charge separation. The performance of V2AlC@V2O5/TiO2 composite for photocatalytic CO2 reduction with water and bi-reforming of methanol was performed using a fixed bed and monolith photoreactor. Using V2AlC@V2O5/TiO2 with a fixed bed reactor and methanol–water mixture, a CO yield of 13.75 mmol g−1h−1 was produced, 26.39 and 38.19-fold higher than using water and pristine TiO2, respectively. Similarly, CH4 production was 1.97 and 12.33 folds higher than using water and TiO2 only, whereas, using water, production of H2 was not detected. The higher photoactivity of the composite with methanol was due to efficient photo-induced carrier separation due to the synergistic effect of V2AlC/V2O5 and more production of protons. Using a monolith photoreactor, CH4, CO and H2 production rates of 55.44, 35.51 and 1.638 mmol g−1h−1 were obtained, 166.50, 2.58 and 3.05 times more than those produced using a fixed bed reactor. This significantly higher photoactivity with monolith photoreactor was due to higher photon flux utilization with surface reactions, resulting in more production and utilization of photoinduced charge carriers. The highest QY after five consecutive cycles was 48.374, 25.358 and 1.51 % for CH4, CO and H2, which is 200.5, 2.54 and 3.87 folds higher than using the fixed bed, respectively. This work provides a new approach to designing and fabricating higher efficient and stable photocatalytic system for CO2 recycling, and it can be further employed for other energy-related applications.

Effects of initial alkalinity and elemental sulfur: dolomitic limestone ratio on autotrophic denitrification of poultry wastewater

Autotrophic denitrification from elemental sulfur is an alternative to heterotrophic denitrification for substrates with a low C/N ratio. In this process, nitrogen compounds are reduced from elemental sulfur instead of carbon, as in the conventional process. However, it may be limited by the low concentration of alkalinity in these effluents. Thus, this study evaluated the performance of autotrophic denitrification of nitrified poultry effluent in four fixed bed reactors with a ratio of elemental sulfur/dolomitic limestone (1:0, 3:1, 1:1, 1:3 v/v) under conditions of the decline of initial alkalinity (1000, 800, 600, 400 and 200 mg CaCO3 L-1). Denitrification efficiencies greater than 84.8% were observed in conditions of initial alkalinity greater than 600 mg CaCO3 L-1 in the four reactors, associated with maximum yields of 445.1 mg SO4-2 L-1. The slow dissolution of dolomitic limestone may have impaired denitrification efficiency in conditions of initial alkalinity lower than 600 mg CaCO3 L-1. The autotrophic denitrification process proved viable for the treatment of nitrified effluent, and its efficiency was linked to the food substrate and the dissolution of dolomitic limestone.

Influence of pyrolysis temperature on carbon deposition from the perspective of volatile evolution during the ex-situ pyrolysis-catalysis of plastic

To better understand the mechanism of carbon deposition, the ex-situ catalytic pyrolysis of polyethylene (PE) was explored over a FeNi/Al2O3 catalyst, and the evolution of volatiles as well as the yield and structure of carbon products at different temperatures were analyzed in depth by an in-situ atmospheric pressure photoionization high-resolution mass spectrometry (APPI HRMS) combined with a fixed-bed reactor. The results show that raising the pyrolysis temperature (from 500 to 800 °C) reduces carbon product yield and H2 production, and the proportion of carbon nanotubes (CNTs) in the carbon products decreases. The source of carbon products gradually shifts from liquid-phase carbon sources to gaseous-phase carbon sources. Below 700 °C, both the outer diameter and carbon interlayer spacing of CNTs decrease, while above 700 °C, they both increase along with increased distortion of carbon layers. It is also observed that the carbon layers are connected to the catalyst lattice stripes, and the interlayer spacing of carbon layers is greater than the catalyst lattice spacing. In situ mass spectrometry reveals a significant increase in the carbon number and double bond equivalent (DBE) values of volatiles with increasing pyrolysis temperature, but the rate of increase slows down after 700 °C. Volatiles from lower pyrolysis temperatures undergo severe polymerization, upon entering the catalytic zone at higher temperatures, minimizing temperature-induced distinctions. Nevertheless, it remains evident that volatiles from lower pyrolysis temperatures exhibit less pronounced polymerization when exposed to higher catalytic temperatures.

Facile synthesis of super-microporous mesoporous MgO-ZrO2 composites and their adsorption properties for CO2

The composite adsorbents with super-microporous mesoporous structure were synthesized via one-step process. The results showed that the composite adsorbents exhibited uniform spherical particles which formed uniform pore size distribution in the range of 1.48–4.15 nm. When the molar ratio of magnesium to zirconium is 0.5, the composite adsorbent showed the biggest CO2 adsorption capacity of 3.01 mmol/g at the adsorption temperature of 75 ℃ and the intake flow rate of 60 mL/min with the fixed-bed catalytic reaction device under atmospheric pressure. After three cycle tests, the adsorption capacity of the adsorbent for CO2 was still 97.3 %, indicating that good adsorption stability.

Modeling and simulation of biodiesel synthesis in fixed bed and packed bed membrane reactors using heterogeneous catalyst: a comparative study

In this study, modeling and simulation of biodiesel synthesis through transesterification of triglyceride (TG) over a heterogeneous catalyst in a packed bed membrane reactor (PBMR) was performed using a solid catalyst and compared with a fixed bed reactor (FBR). The kinetic data for the transesterification reaction of canola oil and methanol in the presence of solid tungstophosphoric acid catalyst was extracted from the published open literature. The effect of reaction temperature, feed flow rate, disproportionation of the reactants, and reactor length on the product performance was investigated. Two-dimensional and heterogeneous modeling was applied to PBMR and the resultant equations were solved by the Matlab software. Moreover, the velocity profile in the membrane reactor was obtained. The results showed the best conditions for this reaction are 180 °C, the molar ratio of methanol to oil equal 15:1, and the input flow rate of 0.5 mL/min. In this condition, a conversion of 99.94% for the TG can be achieved in the PBMR with a length of 86 cm while a length of 2.75 m is required to achieve this conversion of the FBR. Finally, the energy consumption for the production of 8000 ton/y biodiesel in a production plant using the PBMR and the FBR was obtained as is 1313.24 and 1352.44 kW, respectively.

Pyrolysis of oil palm trunk biomass using a fixed bed reactor to produce raw material for bio-carbon black

The abundance of palm oil plantation waste in Indonesia can be utilized as a raw material for making carbon black, which currently relies on fossil fuel-based raw materials. Out of the five types of palm oil biomass waste, including empty fruit bunches (EFB), palm kernel shells (PKS), palm mesocarp fibers (PMF), oil palm fronds (OPF), and oil palm trunks (OPT), one will be chosen as the raw material for carbon black production. Palm oil biomass waste typically has a relatively high ash content. To reduce the ash content, the biomass must first undergo pyrolysis to transform it into pyrolysis oil. The higher the carbon content and the lower the oxygen content, the more the pyrolysis oil meets the criteria for replacing crude oil. Among the criteria mentioned, the lowest ash content is found in palm kernel shells (1.4%). The highest carbon content is in palm trunks (55.8%), while the lowest oxygen content is also in palm kernel shells (34.5%). Palm kernel shells are the best palm oil biomass that can be used as a raw material for carbon black. However, because palm kernel shells are commonly used as boiler fuel, the second choice is palm trunks due to their high carbon content. Pyrolysis experiments were conducted using palm trunk biomass to produce bio-oil, which would be further processed into carbon black. The palm trunks were divided into three parts: outer trunk, middle trunk, and core trunk. The biomass size was also varied, with sizes of 20 mesh and 40 mesh. The pyrolysis process used a fixed bed reactor with a heating rate of 3°C/minute, reaching a pyrolysis temperature of 600°C, and maintaining that temperature for 1.5 hours. The highest yield of bio-oil obtained was from the outer trunk with a biomass size of 40 mesh (36.8%). Similarly, for a size of 20 mesh, the highest yield was also from the outer trunk (35.7%).

An Exploration of various Fructooligosaccharides production methods using novel engineered enzymes with innovative core-shell chitosan beads

This study investigates Fructooligosaccharides (FOSs) production as prebiotics to promote gut health and overall well-being. Various production methods for FOSs were explored, leveraging novel engineered inulosucrase (IN) and levansucrase (LV) enzymes. The methodologies included batch stirred reactors with free enzymes and fixed-bed reactors utilizing enzymes immobilized on hydrogel chitosan beads (HGBs) and core-shell chitosan beads (CSBs). The study found that free enzymes exhibited the highest sucrose consumption rates, with IN achieving 142.8 g/L∙h and LV achieving 82.9 g/L∙h. However, CSB-immobilized enzymes demonstrated substantial enzyme savings (55% and 41% reduction in IN and LV consumption, respectively) through reuse across multiple cycles, while delivering superior FOSs yields. CSB-immobilized enzymes outperformed HGB-immobilized enzymes in terms of immobilization efficiency, activity recovery, sucrose conversion, FOSs yields, and repeatability. A novel reactor setup involving interconnected fixed-bed reactors with different enzymes in series produced promising results, generating novel FOSs species alongside expected I-FOSs and L-FOSs. Consumable cost analysis indicated that while free enzyme usage is initially cost-effective (5.09–7.06 USD/kg FOSs), significant increases in LV prices could make CSB immobilization a cost-competitive alternative. This study highlights the potential of innovative enzyme immobilization strategies and reactor designs for efficient FOSs production, considering both performance and economic feasibility.

Catalytic upgrading of Naomaohu coal pyrolysis volatiles over NiAl and NiLiAl oxides

Catalytic upgrading of volatiles is an essential technology to improve the product distribution of pyrolysis for the clean and efficient utilization of low-rank coals. In this work, novel acid-base bifunctional catalysts composed of Ni/Li/Al oxides were designed and prepared using LDH precursors with tunable chemical composition and structural properties. The catalysts were systematically characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), physisorption, NH3-temperature programmed desorption (NH3-TPD), CO2-temperature programmed desorption (CO2-TPD), H2-temperature programmed reduction (H2-TPR), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). A two-stage fixed bed reactor was employed to evaluate the performance of the catalysts. Characterization results suggest that the crystal size of NiO and the surface area of the catalyst decreased with increasing Li content and decreasing Ni content in the catalyst, while the pore volume and pore diameter were positively correlated with Li content. Moreover, the addition of Li reduced the amount of weak acid sites and raised the amount of total basic sites. Consequently, the bifunctional catalysts boosted the yield of light tar and the contents of aromatics and phenols in tar. Specifically, with the highest total acid sites (569 μmol/g) promoting the cracking of heavy pitch components, Ni2.5Li0.5Al1 decreased the content of pitch in tar to 23.8 wt%, representing a 42.7 % drop from the corresponding non-catalytic pyrolysis. Accordingly, it improved the light tar yield to 7.2 wt%, which was 18 % higher than non-catalytic pyrolysis. 450 °C is identified as a suitable temperature for the catalytic upgrading of volatiles from Naomaohu coal; higher catalysis temperatures at 500 °C and 550 °C led to lower tar yield and lower phenols content, along with higher gas yield and more carbon deposition.

Dual-functionalized aramid fiber as an efficient heterogeneous acid-base bifunctional catalyst for the one-pot tandem reaction

Acid-base bifunctional catalysis represents a significant approach for achieving enzyme-like catalytic activity. In this study, we present a concise and direct approach for constructing acid-base bifunctional aramid fiber catalysts, enabling one-pot tandem deacetalization-Knoevenagel reactions in an aqueous environment. The fiber catalysts were conveniently prepared from commercially available aramid fiber using a straightforward two-step procedure, and comprehensively characterized using various detection techniques. Additionally, the acid-base cooperativity of the AF catalyst was effectively controlled through the manipulation of the acid-base ratios within the catalysts. Notably, the AF-SN1/2 catalyst exhibited superior catalytic activity in the one-pot tandem deprotection-Knoevenagel reaction at room temperature, resulting in the production of high yields. Moreover, the AF-SN1/2 catalyst demonstrated exceptional recyclability and performed admirably in a scaled-up experiment utilizing a straightforward fixed-bed reactor. These findings suggest that the AF-SN1/2 catalyst holds significant promise for future applications in cleaner industrial processes.

Fenton-like water disinfection using fixed-bed reactor filled with a CoFe2O4 catalyst: Mechanisms, the impact of anions, electromagnetic heating, and toxicity evaluation

This work is a pioneering study demonstrating a promising breakthrough in water disinfection using a cobalt ferrite catalyst in a fixed bed. The performance of CoFe2O4 in E. coli inactivation is due to HO• radicals generated in the Fe3+/Fe2+ and Co3+/Co2+ redox cycles. In contrast to existing reports using cobalt ferrite nanoparticles, the bulk cobalt ferrite provides long-lasting catalytic performance in a flow reactor. The positively charged surface of cobalt ferrite attracts negatively charged E. coli membranes, which enhances disinfection. The CoFe2O4 catalyst was synthesized by the flow co-precipitation method, which allows obtaining kilogram quantities needed for industrial applications. The efficiency of E. coli inactivation was studied as a function of H2O2 concentration. For the first time, the reactor with a CoFe2O4 catalyst was additionally boosted by an electromagnetic field to decompose H2O2 and inactivate bacteria. The electromagnetically heated CoFe2O4/H2O2 system provides a significant 6 log bacterial inactivation. Importantly, cobalt ferrite is very stable under operating conditions. Only a negligible leaching of Fe and Co ions was observed. The presence of inorganic anions was beneficial for the bacterial inactivation. Ecotoxicological analysis revealed the absence of the toxicity of the treated water after using CoFe2O4/H2O2 with electromagnetic heating in the presence of bicarbonate ions. The results show that the magnetic cobalt ferrite is a promising, durable, heterogeneous catalyst for large-scale water disinfection.

Chemical looping reforming of the micromolecular component from biomass pyrolysis via Fe2O3@SBA-16

AbstractTo solve the problems of low gasification efficiency and high tar content caused by solid–solid contact between biomass and oxygen carrier in traditional biomass chemical looping gasification process. The decoupling strategy was adopted to decouple the biomass gasification process, and the composite oxygen carrier was prepared by embedding Fe2O3 in molecular sieve SBA-16 for the chemical looping reforming process of pyrolysis micromolecular model compound methane, which was expected to realize the directional reforming of pyrolysis volatiles to prepare hydrogen-rich syngas. Thermodynamic analysis of the reaction system was carried out based on the Gibbs free energy minimization method, and the reforming performance was evaluated by a fixed bed reactor, and the kinetic parameters were solved based on the gas–solid reaction model. Thermodynamic analysis verified the feasibility of the reaction and provided theoretical guidance for experimental design. The experimental results showed that the reaction performance of Fe2O3@SBA-16 was compared with that of pure Fe2O3 and Fe2O3@SBA-15, and the syngas yield was increased by 55.3% and 20.7% respectively, and it had good cycle stability. Kinetic analysis showed that the kinetic model changed from three-dimensional diffusion to first-order reaction with the increase of temperature. The activation energy was 192.79 kJ/mol by fitting. This paper provides basic data for the directional preparation of hydrogen-rich syngas from biomass and the design of oxygen carriers for pyrolysis of all-component chemical looping reforming.

Study on H3PO4-activated carbon catalytic co-pyrolysis of bamboo and LDPE to poly-generation syngas and aromatics at low temperature

Biomass-derived carbon activated by H3PO4 was adopted to catalytic co-pyrolysis of bamboo and low-density polyethylene (LDPE) to produce syngas and aromatics on a fixed bed reactor. Effects of LDPE ratio in the feedstock, catalytic co-pyrolysis temperature and ratio of catalyst to feedstock on the yields and compositions of the products were investigated. The increase of LDPE ratio in liquid first improved and then reduced the relative content of aromatics, while it showed a positive effect on the yield and the H2/CO ratio of gas. 500℃ was an optimum temperature, under which the relative content of aromatics in liquid kept higher, meanwhile, avoided the undesirable polymerization reactions of monocyclic aromatics. At the same time, the content of H2 in gas reached a maximum (59.3%), which was in favor of poly-generation. H3PO4-activated carbon catalyst (H3PO4-ACC) with abundant functional groups on surface catalyzed cracking, hydrodeoxygenation, cyclization and aromatization reactions so as to facilitate the generation of aromatics. Non-condensable gas was dry reformed on P-ACC at the expense of CO2, CH4 and CO to generate char and H2. When the reaction condition was at a LDPE ratio of 50%, a catalyst/feedstock ratio of 2:1 and at 500℃, the relative content of aromatics in liqiud was 81.65% and the proportion of syngas component in gas was 79.73%. The volume ratio of H2/CO approached to 3:1 in gas under this condition. H3PO4-ACC catalytic co-pyrolysis of bamboo and LDPE could obtain high quality gas and liquid products at a relative low reaction temperature, which provided a new research idea on high-value application of biomass and waste plastics.

Green catalyst innovation: Enhanced Fischer-Tropsch synthesis using potassium-promoted cobalt catalysts supported on pyrolyzed peanut shells and Cladophora Glomerata modified biochars

This paper explores pyrolysis potential for effective modified biochar (MB) production, serving as a green and novel carbon-based catalyst support in Fischer-Tropsch to olefins synthesis. For this purpose, the MB produced from the pyrolysis of pre-treated Peanut shell (PS) and Cladophora glomerata algae (CG) was used as a high porosity support for cobalt catalyst synthesis. The impregnation technique was applied to prepare the cobalt catalysts, and the catalysts were promoted with potassium. Various methods examine catalysts physico-chemical properties. After 10 h of reduction at 400 °C, the catalysts' activity and selectivity were studied in a fixed-bed reactor. TEM images show that the metal particles are suitably distributed on the porous surface of the modified biochars. The majority of the particles were between 5 and 15 nm in size. Also, TPR results indicate a suitable metal dispersion of about 10% and good catalyst reducibility have been achieved. The cobalt catalysts produced on MBs of CG and PS exhibited FT rates of 0.245 and 0.223 (g HC/g cat.h), with CO conversion rates of 50.25% and 45.68% in each case. Finally, K-promoted cobalt catalysts supported on MBs of CG and PS showed the α-olefins selectivities of 38.67% and 35.49% for C2-C13 hydrocarbons, respectively.