High-pressure Reactor Research Articles

Effect of different pre-treatment techniques on thermogravimetric characteristics and kinetics of lignocellulosic biomass pyrolysis

In this study, effect of pre-treatments on biomass pyrolysis kinetics was evaluated. Fir wood sawdust (F), pine wood sawdust (P) and hazelnut shell (H) were selected as raw biomass sample. Acidic pre-treatment was applied by using 1M-H2SO4 at room conditions and hydrothermal pre-treatment applied by using high pressure and temperature reactor. Thermogravimetric analysis was executed to specify thermal degradation behavior of the samples. Thermogravimetric analysis was also used to determine kinetic parameters of thermal degradation for biomass and pre-treated biomass samples. Having knowledge thermal degradation behavior and kinetic parameters of pyrolysis process such as activation energy and reaction rate are very important for reactor design. Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW) and Coats-Redfern (CR) methods were used to investigate the effect of different pre-treatment techniques on the kinetic parameters. Activation energies of pyrolysis reactions for F, P and H were found as 158.47 ± 1.08 kJ/mol, 126.0 ± 1.78 kJ/mol and 158.66 ± 1.24 kJ/mol, respectively. The calculated activation energy values increased while acidic and hydrothermal pre-treatment were applied to each biomass samples. In conclusion, acidic and hydrothermal pre-treatments influenced the serial and parallel reaction rates during the thermal degradation process and the calculated activation energy values changed accordingly. Inorganics that catalyzed the pyrolysis reactions were removed by acid pre-treatment. The condensed species during hydrothermal pre-treatment prevented the easy volatilization. As a result of experimental studies and kinetic calculations, it has been determined that pre-treatments applied to biomass increased the activation energy value in thermal degradation reactions.

Magnetic ionic liquid catalyst functionalized with antimony (III) bromide for effective glycolysis of polyethylene terephthalate

In a previous study, we demonstrated the efficient depolymerization of polyethylene terephthalate (PET) through glycolysis using antimony (III) oxide, a commonly used catalyst in PET synthesis. In the present research, we introduce a novel approach involving the synthesis of a magnetic bifunctional ionic liquid, Fe3O4@PMIM.SbBr4, containing only 2.2 wt% of antimony. The aim is to reduce the required antimony dosage for the reaction and enable its facile recovery and reuse. By employing this catalyst in PET chemical recycling through glycolysis to generate bis (2-hydroxyethyl) terephthalate (BHET) monomer, we achieved 100% PET conversion with a 96.4% yield and selectivity for BHET. This outcome was obtained using a catalyst loading of 6.0 wt% at 200 °C and 0.6 bar in a high-pressure reactor. We explored the impact of catalyst loading on BHET yield and conducted a comparative assessment of the Fe3O4@PMIM.SbBr4 catalyst against antimony (III) bromide, and another synthesized unsupported antimony-containing ionic liquid. Our results revealed the superior catalytic activity of the magnetic ionic liquid catalyst in PET glycolysis. The utilization of this catalyst offers promising potential for PET glycolysis due to its effortless separation using an external magnet, ability to produce highly pure BHET, and recyclability for repetitive use.

Upgrading of soybean meal-derived bio-oil via hydrodeoxygenation over [formula omitted]-Al2O3-supported monometallic and bimetallic catalysts

The characteristics of bio-oil derived from soybean meal were upgraded by the hydrodeoxygenation (HDO) over monometallic and bimetallic catalysts. The heating value of the bio-oil remained low due to its high oxygen content. To minimize oxygenated compounds in the bio-oil, the HDO was performed in a high pressure reactor at 300 °C under hydrogen pressure. The catalysts utilized in this reaction were Ni/γ-Al2O3 and Ni-Co/γ-Al2O3 produced using an incipient wetness impregnation approach. Several aspects influencing bio-oil upgrading were investigated, including catalyst type, nickel and cobalt ratio, catalyst amount, and reaction time. When compared to the oil before upgrading, the bio-oil after HDO with all catalysts had a better quality with reduced oxygen and greater carbon contents. The Ni/γ-Al2O3 catalyst was more efficient than the bimetallic catalysts in terms of reducing oxygen content and increasing the heating value of the pyrolysis oil. The pyrolysis oil with the lowest oxygen content was produced by the 1% nickel on alumina catalyst, resulting in the high heating value (HHV) of 37.4 MJ/kg. The catalyst amount of 2.5 %wt and the reaction time of 1 h were the suitable conditions for the HDO of soybean meal-derived bio-oil.

Modeling and Simulation of a Multizone Circulating Reactor for Polyethylene Production with Internal Cooling.

Polyolefins play a role in industries and are typically manufactured using two types of reactors: high-pressure tubular reactors and fluidized bed reactors. An innovative technology called the Multizone Circulating reactor (MZCR) has emerged, which introduces an innovative approach with interconnected polymerization zones creating a continuous loop of polymer flow. This study focuses on modeling and simulating ethylene gas phase polymerization within the MZCR in the presence of internal cooling to gain insights into its behavior. To achieve this, a comprehensive computational fluid dynamics (CFD) simulation was developed. It considered momentum, material, and energy balance aspects. The model equations were solved using the finite difference method in COMSOL Multiphysics version 6.1. The investigation primarily focused on studying the impact of incorporating a cooler into the riser section on the temperature profile within the reactor and ethylene conversion. The presence of this cooler resulted in a reduction in temperature change along the riser from approximately 8.0 °C to 4.0 °C. Moreover, it led to an increase of 7%, in ethylene single-pass conversion.

Experiment and simulation of hydrogen oxidation in a high-pressure turbulent flow reactor

Hydrogen oxidation has a complex dependence on pressure. Despite the well-known, reverse S-shape explosion limits, variation of hydrogen oxidation reactivity with pressure has rarely been investigated in a quantitative manner, particularly in the peninsula between the second and third ignition branches when the overall reactivity is low. This work investigates hydrogen oxidation in a turbulent flow reactor at 10 to 48 bar with an inlet temperature of 950 K and an equivalence ratio of 0.03–0.05, which complements our recent study at 1–8 bar in the same reactor (Lu et al. Proc. Combust. Inst. 2021, 243–250). The elevated pressures show a weak promoting effect, in contrast to the strong inhibiting effect at lower pressures in crossing the second ignition branch. Analyzing the hydrogen consumption rates across the pressure range revealed that the reactivity remains at a low level and is barely affected by pressure between 2 and 20 bar, suggesting the existence of a broad low-reactivity valley on the temperature–pressure plane which could be potentially important for practical applications.The measured species-time concentrations, combined with ignition delays selected from the literature, are used to develop a new hydrogen oxidation model focusing on hydrogen autoignition behavior. A comprehensive review of elementary reactions incorporating the latest updates for the rate coefficients is conducted to determine the prior uncertainties. A global optimization method incorporating random sampling and high-dimensional model representation is used to identify the most sensitive reactions and to constrain their uncertainty with the selected experimental targets. An optimized model is then obtained which shows excellent agreement with hydrogen autoignition experiments.

Treatment with Marstacimab for People with Severe Hemophilia a or B: a Plain Language Summary of the results from a short-term study and a longer-term study

What is this summary about? This is a summary of the results from two clinical studies of treatment for men with severe hemophilia A or B. The studies were published in the British Journal of Haematology. People with hemophilia either have low amounts of clotting factors or are missing certain clotting factors in their blood. The severity of hemophilia is found out by a blood test. There are medicines that people with hemophilia can take to replace the missing clotting factor. However, sometimes the body thinks the clotting factor used to treat hemophilia is a foreign substance and produces antibodies to destroy it (called inhibitors) which may slow down or stop blood clotting. What were the results? The studies showed that men with hemophilia had fewer bleed events while taking marstacimab than before this treatment. The results were similar for all doses of marstacimab tested. Overall, the side effects with marstacimab were generally acceptable. Two men had to stop taking marstacimab because of side effects in the short-term study. The most common side effects were high blood pressure and injection site reactions. Most of these reactions were mild or moderate. What do the results mean? These studies showed that marstacimab could help prevent bleeding in men with hemophilia A or B, with or without inhibitors. The results of this study may differ from those of other studies. Physicians should make treatment decisions based on all available evidence and not just on the results of a single study. Larger studies of marstacimab involving more people with hemophilia A or B have started.

Design of a New Method for Oxidizing Polypropylene Wax through the Scraper Reactor and Its Characterization

In this paper, a new scraper reactor is developed to oxidize polypropylene wax, and the reactor is studied through the characterization of the product. Compared with the traditional polyolefin wax high-pressure reactor, the scraper reactor made all samples heated evenly through the outer wall heating, effectively avoiding the problem of inconsistent reaction progress caused by uneven heating. The scraper constantly updates the interface, making the product fully in contact with the air and ensuring the atmosphere conditions for introducing polar groups. The scraper reactor not only simplifies the reaction conditions greatly but also saves the cost of oxidation. The scraper reactor replaces the traditional high-pressure stirring reactor, the membrane scraper in the reactor replaces the traditional stirring, and the air is used as the oxidant. A one-step reaction could obtain high-quality oxidized polypropylene wax (OPPW). The reaction time and temperature effects on OPPW products in new oxidation equipment are discussed. Through oxidation reaction, polar groups such as -C=O and -COOH are introduced into PPW to perform better in the polar environment and improve its thermal stability.

Large-Scale Ex Situ Tests for CO2 Storage in Coal Beds

This publication discusses the experiments and findings of project ROCCS (Establishing a Research Observatory to Unlock European Coal Seams for Carbon Dioxide Storage), which aimed to investigate the potential for carbon dioxide storage in coal seams. The project involved large-scale ex situ laboratory tests, where CO2 was injected into an experimental coal seam using a high-pressure reactor at the Central Mining Institute in Poland. The reactor simulated underground conditions, and the experimental coal seam measured 3.05 m in length with a cross-section of 0.4 × 0.4 m. Parameters such as gas flow, temperatures, and pressures were monitored during the experiments. In the study conducted, the sorption capacity of coal from the Polish mine “Piast-Ziemowit” for CO2, at a sorption pressure of 30 bar, was determined to be 4.8% by weight relative to the raw coal mass. The data collected from these ex situ tests can support the design of a potential commercial-scale CO2 storage installation.

Experimental investigation on in-situ hydrogen generation from depleted heavy oil reservoir by gasification

Fossil energy has been confirmed as the primary raw material for hydrogen generation in chemical factories. In-situ hydrogen generation from depleted oil reservoirs has been considered a prominent technology for hydrogen generation, accompanied by harmful gas storage, over the past few years. In this study, the effects of temperature, reaction time, distinct porous media, and oil/water ratio on hydrogen generation were investigated by simulating in-situ heavy oil gasification using high-temperature and high-pressure reactors. As indicated by the results, besides hydrogen, methane and carbon dioxide were also largely generated in the gasification process through water gas shift, oxidation, aquathermolysis, pyrolysis, and so forth. The result suggested that temperature and oil/water ratio exerted relatively significant effects on hydrogen generation due to the boosted forward reaction of water gas shift and steam reforming. Moreover, oxygen would prefer an oxidation reaction with oil instead of hydrogen. It was expressed that the hydrogen fraction decreased and remained constant as residence time went on due to less carbon monoxide generation, and arriving at equilibrium, whereas the gas yield tend to increase. The metallic oxides notably catalyzed hydrogen generation. Some novel insights gained in this study are conducive to achieving high-efficiency hydrogen generation through in-situ heavy oil gasification.

Comprehensive thermal properties of ternary eutectic molten salt/nanoparticles composite phase change materials for high–temperature thermal energy storage

Chlorine and fluorine salts are very promising thermal storage media for high–temperature thermal energy storage (TES) systems. In this study, NaCl–KCl–NaF/nanoparticles composite phase change materials (CPCMs) were employed by an advanced high–temperature and high–pressure reactor. NaCl–KCl–NaF was adopted as the BS, while CuO and Al2O3 nanoparticles have been uniformly dispersed in different ratios to generate CPCMs from the base salt (BS). Microscopic characterization, thermal properties characterization, and economic analysis of CPCMs and the BS were performed. The findings revealed that the best results were obtained when the BS was added with 0.5 wt percent Al2O3 and 0.5 wt percent CuO nanoparticles, CPCMs have improved solid/liquid thermal conductivity by a factor of 3.70 and 1.84, and TES density by a factor of 1.13, while reducing the cost per unit of TES density by approximately 26.8%. In addition, the CPCMs and BS possess excellent operating temperature range and thermal stability, whereby they are applicable in high–temperature TES systems.

Bio-oil and biochar production from Ageratum conyzoides using triple-stage hydrothermal liquefaction and utilization of biochar in removal of multiple heavy metals from water

Production of low-cost biomass and its utilization for producing cost effective and eco-friendly bioenergy as well as for removing heavy metals from water can be explored as an approach to meet the sustainable development goals. In light of the above-mentioned study, hydrothermal liquefaction (HTL) of Billy goat weed (BGW; Ageratum conyzoides) was carried out to produce bio-oil. In addition, the residual biochar from the HTL process was activated to obtain Act-BC and was further modified to produce MnO2-loaded biochar (Act-BC@MnO2-25%). The HTL of BGW was done at three different temperatures, i.e., 250 °C, 350 °C and 450 °C in a high-pressure batch reactor to maximize the bio-oil yield. Also, two different HTL methods i.e., single-stage HTL and triple-stage HTL of BGW were compared and discussed in detail. The bio-oil obtained via the triple-stage HTL was rich in carbon, hydrogen, and nitrogen. It also showed a higher heating value (HHV) and bio-oil yield (46%) than the single-stage. The residual biochar obtained at 450 °C (Act-BC) and MnO2 modified (Act-BC@MnO2-25%) were then tested to adsorb multiple heavy metal (i.e., Pb(II), Cd(II), Cu(II), and Ni(II)) from water. The kinetics data obtained from the adsorption experiment with Act-BC@MnO2-25% were well fitted to PSO kinetics model. The isotherm data were well aligned with the Langmuir model; the adsorption capacity of Act-BC@MnO2-25% was estimated to be 198.70 ± 11.40 mg g−1, 93.70 ± 6.60 mg g−1, 78.90 ± 7.20 mg g−1 and 30.50 ± 2.10 mg g−1 for Pb(II), Cd(II), Cu(II), and Ni(II), respectively. Furthermore, Act-BC@MnO2-25% remained active for metal ions absorption even after six consecutive uses. The result obtained from this study clearly demonstrates that the triple-stage HTL of BGW is a promising technology to achieve both remediation of metal-contaminated water and production of bioenergy.

Selective Synthesis of Perovskite Oxyhydrides Using a High-Pressure Flux Method.

Oxyhydrides with multi-anions (O2- and H-) are a recently developed material family and have attracted attention as catalysts and hydride ion conductors. High-pressure and high-temperature reactions are effective in synthesizing oxyhydrides, but the reactions sometimes result in inhomogeneous products due to insufficient diffusion of the solid components. Here, we synthesized new perovskite oxyhydrides SrVO2.4H0.6 and Sr3V2O6.2H0.8. We demonstrated that the addition of SrCl2 flux promotes diffusion during high-pressure and high-temperature reactions, and can be used for selective synthesis of the oxyhydride phases. We conducted in-situ synchrotron X-ray diffraction measurements to reveal the role of this flux and reaction pathways. We also demonstrated the electronic and magnetic properties of the newly synthesized oxyhydrides and that they work as anode materials for Li-ion batteries with excellent reversibility and high-rate characteristics, the first case with an oxyhydride. Our synthesis approach would also be effective in synthesizing various types of multi-component systems.

Design of bi-functional Ni-zeolites for ethylene oligomerization: Controlling Ni speciation and zeolite properties by one-pot and post-synthetic Ni incorporation

The design of diverse Ni-zeolites has been performed attempting to control different physico-chemical properties of the zeolite supports as well as the Ni speciation to study their influence on the industrially relevant ethylene oligomerization reaction. In this sense, Ni-containing medium-pore MFI and large-pore BEA zeolites have been synthesized with different particle sizes, Si/Al molar ratios and following different Ni-incorporation strategies (one-pot versus post-synthesis). Characterization techniques reveal the preferential presence of cationic Ni2+ and NiO nanoclusters inside the zeolitic pores when Ni has been incorporated by post-synthesis impregnation or one-pot approaches, respectively. The presence of Ni2+ species, rather than other factors, mainly governs olefin oligomerization under near-ambient pressures, guiding preferentially towards C4-C6 olefins as main products. Crystal size, acidity and/or Ni incorporation methodology, on the other hand, play key roles under high-pressure reaction conditions, resulting in the formation of heavier olefins, especially in zeolites containing less cationic nickel, larger proportion of NiO clusters and higher Brønsted acid site density.

Correction to: Conversion of wheat bran into fermentable sugars using deep eutectic solvent pretreatment in a high-pressure reactor

Correction to: Conversion of wheat bran into fermentable sugars using deep eutectic solvent pretreatment in a high-pressure reactor

Evaluation of Thermochemical Treatments for Rice Husk Ash Valorisation as a Source of Silica in Preparing Geopolymers.

The use of geopolymers has revolutionized research in the field of construction. Although their carbon footprint is often lower than that of traditional mortars with Portland cement, activators such as sodium silicate have a high environmental impact in the manufacturing of materials. Employing alternative alkali sources to produce geopolymers is necessary to obtain materials with a lower carbon footprint. The present research explores the use of rice husk ash (RHA) as an alternative source of silica to produce alkaline activators by four methods: reflux; high pressure and temperature reaction; thermal bath at 65 °C; and shaking at room temperature. To evaluate the efficiency of these methods, two types of experiments were performed: (a) analysing silica dissolved by the filtering/gravimetric method; and (b) manufacturing mortars to compare the effectiveness of the treatment in mechanical strength terms. The percentages of dissolved silica measured by the gravimetric method gave silica dissolution values of 70-80%. The mortars with the best mechanical strength results were the mixtures prepared with the thermal bath treatment at 65 °C. Mortar cured for 1 day (at 65 °C), prepared with this activator, yielded 45 MPa versus the mortar with commercial reagents (40.1 MPa). It was generally concluded that utilising original or milled RHA in preparing activators has minimal influence on either the percentage of dissolved silica or the mechanical strength development of the mortars with this alternative activator.

Highly Efficient and Effective Process Design for High-Pressure CO2 Photoreduction over Supported Catalysts

The photocatalytic reduction of CO2 into solar fuel is considered a promising approach to solving the energy crisis and mitigating the environmental pollution caused by anthropogenic CO2 emission. Some powder photocatalysts have been demonstrated as efficient, but their drifting properties, along with difficult separation (catalyst and product), make continuous mode reaction very challenging, particularly in the liquid phase. In order to make this process commercially viable and economically more efficient, we have developed a simple and scalable method for immobilizing TiO2 P25 over the surface of glass slides using an organic-based surfactant. Improved adhesion properties and the homogeneous dispersion of catalyst nanoparticles were achieved. A holder was designed with 3D printing technology in such a way that it can hold up to six slides that can be dipped simultaneously into the suspension or solution of desired materials for a uniform and homogeneous deposition. The resulting surfaces of the dip-coated materials (e.g., TiO2 P25) were further modified by adding metallic nanoparticles and thoroughly characterized via XRD, DRS UV–Vis, SEM, and SEM–EDX. Photocatalytic tests have been performed for two major applications, viz., hydrogen production via the photoreforming of glucose and the photoreduction of CO2 into different solar fuels. The latter tests were performed in a specially designed, high-pressure reactor with Ag/P25 supported catalysts, which exhibited about three times higher formic acid productivity (ca. 20 mol/kgcat h) compared to the dispersed catalyst, with enhanced stability and recoverability. It is to note that catalysts deposited on the glass slides can easily be recovered and the materials did not show any weight loss. To the best of our knowledge, the obtained formic acid productivity is highest among the published literature.

Transformation of vegetable oils into green diesel over Ni-Mo catalysts supported on titania

Reduced NiMo catalysts supported on titania for transformation of vegetable oils to green diesel have been studied. A series of six catalysts with total metal content equal to 50% and various [Ni/(Ni+Mo)] atomic ratios was prepared following deposition-precipitation method, using urea as precipitating agent. The catalysts were characterized by N2 physisorption, XRD, XPS, H2-TPR, and NH3-TPD. They were evaluated for the transformation of various crude oils, namely sunflower oil, rapeseed oil, soybean oil and cardoon oil, to green diesel, in a high-pressure (40 bar) semi-batch reactor, at 310 °C and under solvent free conditions. A synergistic [Ni/(Ni+Mo)] atomic ratio equal to 0.99 was determined. The catalyst with this formulation exhibited high metallic nickel active surface in combination with high oxygen vacancies population provided by reduced Mo-species. Over this catalyst, the crude vegetable oils were transformed to green diesel achieving yields of 65 ± 2%.

Valorization of Pyrolyzed Biomass Residues for the Transformation of Waste Cooking Oil into Green Diesel

This study aims to utilize biochars derived from residual biomass as supports for Ni-based catalysts. For the preparation of the biochars, byproducts of agro-industrial activities were used, such as espresso coffee residue (C) and rice husks (R). Sufficient quantities of the respective biochars (BioC and BioR) were prepared via pyrolysis at 850 °C of the aforementioned materials under limited oxygen conditions. The biochars were further treated with hot water (WBioC, WBioR), H3PO4 or H2SO4 solution (BioC-P, BioC-S, BioR-P, BioR-S), and NaOH solution (BioC-A and BioR-A), and the obtained solids were characterized using various physicochemical techniques. The biochars produced were microporous with high surface areas (367–938 m2g−1). The most promising biochars were selected as supports for the preparation of nickel catalysts (10 wt.% Ni) with high Ni dispersion (mean crystal size: 8.2–9.8 nm) and suitable acidity. The catalysts were evaluated in a high-pressure semi-batch reactor for the transformation of waste cooking oil (WCO) into green diesel. The 10Ni_BioC-P catalyst exhibited the best performance, resulting in a complete conversion of the WCO but a low hydrocarbon yield (7.5%). Yield improvement was achieved by promoting this catalyst with molybdenum. The addition of Mo increased the hydrocarbon yield by almost three times (19.5%).

METHOD OF QUALIFICATION OF MODERNIZATION OF ACTIVE SAFETY SYSTEMS TO PREVENT HYDRODYNAMIC INSTABILITY

The main reason for the hydrodynamic instability in the start-up mode of the pumps of the high-pressure reactor makeup system is related to the inertial delay in the reaction of the pump head and rate to rapid changes in operating parameters (flow rates, pressure, etc.).The consequences of the hydrodynamic instability in the high-pressure reactor makeup system can be: violation of the conditions for compensating the flow of possible leaks; hydro- and thermal "shocks" and other negative effects in the operating and emergency modes of the reactor.The control armature does not prevent the conditions for the hydrodynamic instability in the transient mode of pump start-up.
 An alternative approach to modernizing the high-pressure reactor makeup system with damping devices is proposed. Based on the performed modelling of the modernized system, the conditions and constructional and technical requirements for the prevention of the hydrodynamic instability in the transient modes of pump start-up were determined.

Conversion of wheat bran into fermentable sugars using deep eutectic solvent pretreatment in a high-pressure reactor

Conversion of wheat bran into fermentable sugars using deep eutectic solvent pretreatment in a high-pressure reactor