Weight Hourly Space Velocity Research Articles

Production of phenol-rich bio-oil from Arundo donax via catalytic pyrolysis over SAPO-31

Herein, the SAPO-31 produced phenol-rich bio-oil from Arundo donax (AD) via catalytic fast pyrolysis (CFP) in a fixed bed. Effective variables including type of catalyst, temperature, weight hourly space velocity (WHSV) and N2 flow rate (Nfr) were evaluated to enhance the CFP. The results showed that SAPO-31 demonstrated selectivity of 80.28 % towards naphtha-range compounds and 33.57 % towards phenolic compounds (PCs) within the naphtha range at 500 °C, Nfr of 300 mL min−1 and WHSV of 1 h−1, contrasting sharply with those of control groups (50.82 % and 14.40 %, respectively), HZSM-5 (67.66 % and 5.51 %, respectively) and Hβ (61.10 % and 25.50 %, respectively). Moreover, SAPO-31 gave the highest bio-oil yielded (26.97 wt%) compared to that of the control group (22.45 wt%), Hβ (22.21 wt%) and HZSM-5 (21.42 wt%). These results indicate that the SAPO-31 self-synthesized exhibits promising capabilities in producing phenol-rich naphtha-range compounds via the CFP of AD.

Experimental investigation on product and temperature distribution in a continuous flow packed-bed reactor for dodecahydro-N-ethylcarbazole dehydrogenation

The dehydrogenation of dodecahydro-N-ethylcarbazole (H12-NEC) generates enormous gas accompanied by intense heat absorption, affecting heat and mass transfer in porous catalysts. A packed-bed reactor equipped with a temperature measurement device was designed to investigate the continuous flow dehydrogenation of H12-NEC. The effects of weight hourly space velocity (WHSV), reaction temperature, catalyst particle size, and pressure were evaluated. The results reveal that the volume flow rate of hydrogen will increase with the increase of WHSV. And the reduction of gas–liquid ratio and catalyst particle size facilitates heat transfer causing a more uniform axial temperature distribution within the reactor. As the temperature rises, the hydrogen yield increases along with more by-products. 456 K and 2 mm of catalyst particle size are determined to be the optimal reaction conditions in the study, achieving the hydrogen production rate of 9.61 molH2·gPd-1·h-1. With pressure increasing, the hydrogen yield gradually decreases, but the decreased evaporation of H12-NEC results in a smaller temperature difference between the reactor and heating wall. A comparison with the thermodynamic equilibrium model reveals that the effect of pressure on chemical equilibrium may be more significant than the temperature.

Study on the Acidic Modification of Mesoporous HZSM-5 Zeolite and Its Catalytic Cracking Performance

Mesoporous HZSM-5 zeolites with nanocrystal stacking morphology were directly synthesized via hydrothermal methods without mesoporous templates. The synthesized mesoporous HZSM-5 was subjected to hydrothermal–citric acid washing treatment. The structural and acidic properties of the samples before and after modification were characterized using various techniques. The catalytic performance for butene conversion to propylene was investigated under atmospheric pressure, 500 °C, and a butene weight hourly space velocity (WHSV) of 10 h−1 in a continuous-flow micro-fixed bed reactor. The results show that propylene selectivity increased significantly from 24.7% before modification to 44%, and propylene yield increased from 22% to 38%. After 2 h of hydrothermal–citric acid washing modification, the catalyst maintained a butene conversion rate of 76% and a selectivity of 47% at 525 °C and a WHSV of 10 h−1 after 130 h of continuous reaction, with a propylene yield of 37%. The results indicate that moderate hydrothermal–citric acid washing modification leads to the removal of aluminum from the zeolite framework, reducing the amount and strength of acid but increasing the mesopore quantity. This helps control the reaction pathways and diffusion of intermediate products, suppresses some side reactions, and improves the selectivity and yield of the desired product, propylene, while significantly enhancing catalytic stability.

Cs-Ba-Ru/La2O3-MgO Catalysts from Microdrop-Confined Pyrolysis for Superior NH3 Synthesis under Mild Conditions.

Support modification is an important way to improve the activity of the Ru/MgO-based NH3 synthesis catalyst. This work synthesized 24 composite MgO-based supports of MOx-MgO (M = La, Zn, etc.) via a microdrop-confined pyrolysis (MDCPy) method and then prepared the corresponding Cs-Ba-Ru/MOx-MgO catalysts using the impregnation method. Under the same NH3 synthesis conditions, the activity of the Cs-Ba-Ru/MOx-MgO catalysts composed of 17 elements such as Pr was significantly lower than that of Cs-Ba-Ru/MgO, while the activity of the Cs-Ba-Ru/MOx-MgO catalysts composed of four elements such as Nd was comparable to that of Cs-Ba-Ru/MgO, and the activity of the Cs-Ba-Ru/MOx-MgO catalysts composed of three elements such as La was significantly higher than that of Cs-Ba-Ru/MgO. Among them, it is clear that La2O3-MgO composite supports have the most significant effect on the improvement of NH3 synthesis performance. Through the optimization of the La/Mg ratio and loading of Ru, the optimal activities achieved ∼7 mol(NH3)/g(Ru)/h with corresponding Ru loading of 0.25-0.5 wt % under mild conditions as follows: H2/N2 ratio of 3:1, temperature of 400 °C, pressure of 3 MPa and a weight hourly space velocity (WHSV) of 96.0 L/gcat/h. In addition, the CsBa-Ru/La2O3-MgO catalyst showed good stability.

Experimental study of the design and performance optimisation of a self-heating methanol on-board reforming reactor for hydrogen production

There is an increasing research on efficient and compact on-board reformer, based on which a serpentine plate type self-heating reformer integrating preheating, reforming and combustion has been designed and fabricated, which can be disassembled and assembled flexibly. In this paper, experiments on the self-heating reformer have been carried out to optimise the differential structure of different chambers. It can be found that: the combustion chamber needs to be partitioned and the resistance loss is small and stable for a long time when the number of partitions is 3. The combustion chamber with O2/CH3OH = 1.5 has the highest wall temperature of 240 °C. Hydrogen yield can be increased to more than two times after optimising the evaporation chamber. The catalyst in the reforming chamber must be uniformly distributed, and the methanol conversion rate is stable at 75 % with a mass of 110 g and Weight Hourly Space Velocity (WHSV) = 8 h−1. The optimum operating conditions of the reactor is WHSV = 8 h−1 with air flow rate of 25 L/min, at which the reactor starts up within 20 min, the hydrogen yield stabilises within 40 min, and the hydrogen yield is 9.8 L/min and remains stable for 120 min.

Electrified catalytic steam reforming for renewable syngas production: Experimental demonstration, process development and techno-economic analysis

Biomass is a key renewable feedstock for producing green fuels; however, renewable feedstock presents a high risk for catalyst deactivation and poor stability. In addition, the heat source of industrial reforming processes comes from fuel combustion and most heat is lost in the flue gas. In this study, a Ni/Al2O3/FeCrAl-based monolithic catalyst with a periodic open cellular structure (POCS) was designed and 3D-printed. A reforming process was then conducted by directly heating the catalyst using electricity instead of fuel combustion. This e-reformer technology was demonstrated in continuous catalytic steam reforming of biomass pyrolysis volatiles. A high H2 yield of ≈7.1 wt % of biomass has been obtained at a steam-to-biomass (S/B) ratio of 4.5, reforming temperature of 800 °C and weight hourly space velocity (WHSV) of 310 h−1, resulting in an energy consumption of 8 kWhel kg−1 biomass (66% energy efficiency). The results show a successful demonstration of the electrified technology with improvement potential; in addition, a process was designed and assessed economically for synthetic natural gas (SNG) production of 80 MWHHV, comparing electrification and partial oxidation in different scenarios.

Performance of mesoporous ceria supported Ru catalysts for oxidative degradation of aqueous solution of plastic monomer bisphenol A in a fixed bed flow reactor: Structure-activity insights, optimization of reaction conditions, kinetics, catalyst stability, and characterization

One of the important defects is the oxygen vacancy on metal oxide surfaces, and the defects function as the active sites in different catalytic reactions. Herein, Ru/CeO2-rod and Ru/CeO2-cube catalysts were prepared via the ESI method, and CeO2-rod and CeO2-cube supports were synthesized by hydrothermal processes. The activity of these catalysts was tested in a high-pressure fixed-bed reactor, and the oxidative degradation of industrial organic raffinate containing the plastic chemical bisphenol A (BPA) was compared with their oxygen vacancy concentration estimated after calcination. The Ru/CeO2-rod catalyst showed higher catalytic activity with 90 % BPA conversion at 453 K, 30 bar, 0.5 % Ru metal content, 15 O2 to BPA molar ratio, and 2 g−1.h−1 BPA feed weight hourly space velocity (WHSV). In contrast, 80 % BPA degradation was achieved using the Ru/CeO2-cube catalyst under similar reaction conditions. The higher oxygen vacancy concentration and the higher interfacial surface area between metal and the support of the CeO2-rod supported Ru catalyst triggered the higher BPA degradation at low oxidation conditions. Besides, the atomic ratio, Ce3+/Ce4+, is lower in the Ru/CeO2-rod catalyst than that of the Ru/CeO2-cube catalyst, indicating the higher Ce4+ available in the catalyst, leading to the higher degradation of BPA. Moreover, the Ru/CeO2-rod catalyst possesses {111} planes that boost the generation of energetic Ru to improve the pursuit of the catalyst. The Weisz-Prater modulus and Thiele modulus values indicated that the surface reaction is the rate limitation step and there is no diffusion limitation. TEM, HRTEM, XPS, Raman, H2-TPR, XRD, CO chemisorption and BET surface area analyzers were used to characterize the catalysts.

Facile synthesis of highly basic, nanocrystalline Fe2O3-NiO composites as promising and durable catalysts for selective dehydrogenation of 2-butanol.

Nanocrystalline Fe2O3-NiO composite catalysts were prepared using a sonication-assisted green preparation method. The prepared catalysts were characterized using different techniques, including thermal analyses (TGA/DTA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, surface area measurements (SBET), and scanning electron microscopy (SEM). The surface basicity of the prepared catalysts was measured using the temperature-programmed desorption of CO2 (CO2-TPD) as a highly acidic probe molecule. The catalytic activity of all the prepared catalysts was tested at a temperature range of 250-325 °C towards the dehydrogenation of 2-butanol to methyl-ethyl ketone (MEK), which is considered a promising fossil fuel alternative and has several industrial applications. The composite catalysts showed better catalytic activity compared to the pure oxides (i.e., Fe2O3 and NiO) due to the strong synergetic effect between the two oxides. Fe2O3 prevented the coke formation over the surface of NiO by the oxygen-scavenging effect of Fe, which promotes the oxidation of the carbonaceous species and increases the catalyst's resistance to deactivation. The effect of weight hourly space velocity (WHSV) on the catalytic activity was tested over a selected catalyst. In addition, the stability and durability of the catalyst were tested across four successive reaction cycles, demonstrating remarkable performance throughout all the reaction cycles.

Highly Stable MOFs-Derived Cu–Co Composite Metal Oxides for Catalytic Oxidation of Toluene

CuCoOx was prepared by in situ pyrolysis of Cu2+ partially substituted MOF-74 precursor with Co-MOF as a template for catalytic oxidation of toluene. T90 (the temperature corresponding conversion of 90%) was only 212°C, at 1000 ppm toluene and weight hourly space velocity (WHSV) of 36 000 mL g–1 h–1. In addition, the conversion was maintained above 97% for 74 h of continuous reaction at 260°C. Even if after 2400 ppm 1,2-dichloroethane (1,2-DCE) poisoning for 2 h, the toluene conversion was still up to 93%, demonstrating excellent stability and resistance to deactivation of catalyst. Furthermore, The high activity and stability of CuCoOx could be attributed to the large specific surface area as well as the high Co2+/Co3+, Cu2+/Cu+, and Olatt/Oads molar ratios.

High-quality utilization of raw coke oven gas for hydrogen production based on CO2 adsorption-enhanced reforming

To realize the high-quality utilization of raw coke oven gas (RCOG), the adsorption-enhanced steam reforming process was purposed for hydrogen production, coupled with the sensible heat recovery and the conversion of the high-energy components (such as tar). For this process, the hydrogen production performance and energy utilization efficiency were focused via reforming experiment and process simulation. Using the prepared bifunctional catalyst (Ni/Ce–CaO–Ca12Al14O33), the enhanced reforming experiment was conducted based on orthogonal design and Taguchi method. Compared to S/C ratio (the mole ratio of steam to carbon in the simulated RCOG) and WHSV (weight hourly space velocity), reforming temperature shows a higher sensitivity to hydrogen production. At 800 °C, the produced H2 amount can achieve 3.86 times of that in the initial RCOG and the H2 concentration in the produced gas can reach 88.38 %, when the S/C ratio was 15 and the WHSV was 0.0847 h−1. Based on the established process model, the energy consumption of RCOG enhanced reforming system was discussed. Compared to traditional hydrogen production technologies, this novel process exhibits a lower energy consumption, just about 62.5 MJ/kg H2, and also shows a higher energy conversion efficiency.

Bimetallic Mn-Cu oxide catalysts for toluene oxidation: Synergistic effect and catalytic mechanism

A series of Mn-Cu composite oxides with different Mn/Cu molar ratios were synthesized via a facile ethanol-redox precipitation method and investigated for the oxidation of toluene. Among as-synthesized MnxCuy catalysts, Mn5Cu1 showed the most excellent toluene catalytic activity at a weight hourly space velocity (WHSV) of 30000 mL∙g−1∙h−1, with 90 % conversion achieved at 212 °C. Furthermore, the Mn5Cu1 catalyst exhibited exceptional thermal stability over a 12-hour period at 215 °C, along with outstanding resistance to H2O in the range of 5 vol% to 40 vol%. As characterized by XRD, BET, XPS, EPR, H2-TPR, and O2-TPD, it was found that Mn5Cu1 possessed a unique three-phase coexisting structure, large specific surface area (57 m2·g−1), plentiful oxygen vacancies, excellent redox capacity, and strong mobility of oxygen, which were attributable to the synergistic effect between Mn and Cu. This strong synergy between Mn and Cu is the underlying reason for the strong catalytic activity of Mn5Cu1. Moreover, toluene-TPD and TPSR results indicated that appropriate Cu loading was favorable for the adsorption and activation of toluene. The potential reaction pathway for toluene oxidation was presented based on in situ DRIFTS characterization. Maleic anhydride was the critical reaction intermediate species.

Modulate synthesis of CeMn solid solution using various alcohols for toluene catalytic oxidation: synergistic effect of Ce-Mn and reaction mechanism

A redox co-precipitation method was employed to synthesize CeMn homogeneous solid solutions, utilizing various alcohols as activating agents. Ethanol effectively orchestrated the precipitation of CeO2 and MnOx, promoting their co-growth. As a result, the CeMn-EA achieved 90 % toluene conversion at 218 ℃ (T90 =218 ℃) with a weight hourly space velocity (WHSV) of 48000 ml/(g·h). It also demonstrated high adaptability to increased WHSV, suggesting its potential for industrial-scale applications. The uniform dispersion of Ce and Mn accelerated the coupling between Ce3+/Ce4+ and Mn4+/Mn3+, engineering numerous oxygen vacancies, which enhanced the activation of gas-phase oxygen and the mobility of lattice oxygen. In situ DRIFTS confirmed that toluene oxidation accommodated both Langmuir-Hinshelwood (L-H) and Mars-van Krevelen (MvK) mechanisms, with benzoate identified as a pivotal intermediate. Enhanced oxygen mobility facilitated the cleavage of the benzene ring, which was the rate-determining step. Additionally, the introduction of H2O significantly enhanced the dissociation and adsorption of toluene and facilitated the activation of gas-phase oxygen. At higher temperatures, H2O could further activate lattice oxygen engaging in toluene oxidation. Environmental ImplicationVolatile organic compounds (VOCs) have emerged as major air pollutants due to the changes in air pollution patterns. They can act as precursors to near-surface ozone and haze. Toluene, a typical VOC, is primarily released from anthropogenic sources and poses significant risks to human health and the environment. Ce-based catalysts have been demonstrated efficiency in toluene oxidation due to their excellent oxygen storage and release properties. This study synthesized CeMn homogeneous solid solutions utilizing various alcohols as activating agents, which possessed abundant oxygen vacancies and optimum oxygen activation capacity to oxidize toluene in time.

Catalytic activity of Co/γ-Al2O3 catalysts for decomposition of ammonia to produce hydrogen

This paper aims to study the performance of Co/meso-Al2O3 catalysts for ammonia decomposition to produce hydrogen. High-performance Co/meso-Al2O3 catalysts were prepared using a sequential metal loading approach. The synthesized catalysts were analyzed by several techniques including X-ray diffraction (XRD), N2 physisorption analysis, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (NH3-TPD) and transmission electron microscope (TEM). The effect of metal loading, decomposition temperature and weight hourly space velocity (WHSV) on the catalyst activity were studied. Temperature-programmed desorption (NH3-TPD) analysis showed the coexistence of weak acidic sites and strong acidic sites in the synthesized catalysts, indicative of weak metal–support interaction. The reaction activation energy of the catalysts followed the order of 26Co-CAT(A) < 9Co-CAT(A) < 16Co-CAT(A) < 5Co-CAT(A) < CAT(A). Particularly, 26 Co-CAT(A) exhibited significantly lower activation energy compared to the other catalyst, which was in line with its catalytic activity. This observation indicated that the cobalt loading in 26 Co-CAT(A) resulted in relatively weaker metal-support interactions, leading to lower desorption energy and thus allowing higher NH3 conversion at lower temperatures. These findings offer valuable insights for the development and optimization of advanced Co-based catalysts, facilitating the sustainable and efficient application of ammonia decomposition.

Close Intimacy between PtIn Clusters and Zeolite Channels for Ultrastability toward Propane Dehydrogenation.

Propane dehydrogenation (PDH) serves as a pivotal intentional technique to produce propylene. The stability of PDH catalysts is generally restricted by the readsorption of propylene which can subsequently undergo side reactions for coke formation. Herein, we demonstrate an ultrastable PDH catalyst by encapsulating PtIn clusters within silicalite-1 which serves as an efficient promoter for olefin desorption. The mean lifetime of PtIn@S-1 (S-1, silicalite-1) was calculated as 37317 h with high propylene selectivity of >97% at 580 °C with a weight hourly space velocity (WHSV) of 4.7 h-1. With an ultrahigh WHSV of 1128 h-1, which pushed the catalyst away from the equilibrium conversion to 13.3%, PtIn@S-1 substantially outperformed other reported PDH catalysts in terms of mean lifetime (32058 h), reaction rates (3.42 molpropylene gcat-1 h-1 and 341.90 molpropylene gPt-1 h-1), and total turnover number (14387.30 kgpropylene gcat-1). The developed catalyst is likely to lead the way to scalable PDH applications.

Thermocatalytic oxidation potential of cobalt(II,III) oxide against gaseous formaldehyde in relation to hydrothermal synthesis temperature

The catalytic activity of various transition metal oxides has been reported to be tuned by controlling their synthesis conditions. In this perspective, the thermocatalytic oxidation performance of cobalt(II,III) oxides (Co3O4) against formaldehyde (FA) is studied in relation to the temperature selected for their hydrothermal synthesis (e.g., 30 (as room temperature (RT)), 60, 120, and 250℃) with the corresponding sample codes as Co3O4-RT, Co3O4-60, Co3O4-120, and Co3O4-250, respectively. The best performing Co3O4-RT records the lowest T90 (temperature required to obtain 90 % conversion) for 50 ppm FA at 72 °C when operated at 0 % relative humidity (RH), 30 mg (catalyst mass: mcat), and 100,000 mL g-1h−1 (weight hourly space velocity). The performance of Co3O4-RT, if assessed in terms of reaction kinetic rate (r) at XFA = 10 %, is 2.02E-02 mmol g-1h−1. According to X-ray photoelectron spectroscopy and temperature programmed characterization analysis, the catalytic activities of Co3O4-RT improve greatly through the synergistic combination of diverse factors (e.g., high Co3+ content, abundant oxygen vacancies (OVs) and surface adsorbed oxygen (Oβ) species, and good surface lattice oxygen (Oα) mobility). The analysis of in-situ diffuse reflectance infrared Fourier transform spectroscopy indicates that the FA should be oxidized into water (H2O) and carbon dioxide (CO2) via dioxymethylene (DOM) and formate (HCOO–) as reaction intermediates. The density functional theory simulations suggest the (111) surface of Co3O4 to be catalytically active against FA. The output of this research is expected to help establish effective strategies for designing high-performance transition metal oxide catalysts for the catalytic oxidation of FA.

Alkylation of Phenol with Methanol over ZSM‐5 Zeolite

AbstractThe catalytic performance of different molecular sieves in the alkylation of phenol with methanol to produce p‐cresol was evaluated, and the acidity and structure of the catalysts were characterized using N2 adsorption–desorption and Fourier transform infrared spectroscopy techniques. It was shown that the catalytic activity of molecular sieves was closely related to their acidic site number, specific surface area, and pore structure. Since Zeolite ZSM‐5 (Zeolites Socony Mobil No. 5) has a relatively small amount of strong acid as well as a small pore size, it is favorable for the diffusion of p‐cresol out of the pores. Therefore, focusing on ZSM‐5, the effects of operating conditions such as weight hourly space velocity (WHSV), phenol/methanol (P/M) ratio, and reaction temperature on the catalytic performance were investigated. The results showed that increasing the WHSV, P/M ratio, and reaction temperature improved the selectivity to cresol. In addition, X‐ray diffraction and Thermal Gravity/Differential Thermal Gravity characterization methods were also carried out for ZSM‐5, and it was found that the deactivation of ZSM‐5 was due to coke deposition and pore blockage on the active site and that the selectivity to cresol could be restored by regenerating the catalyst and covering the strong acid site, which resulted in the reduction of the strong acid site to increase the selectivity of the product.

Promoting effect of potassium over Pd/SiO2 catalyst for ambient formaldehyde oxidation

Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process. Interestingly, in this work, an innovative approach was employed to augmenting the stabilization of noble metals on irreducible carriers supported noble metal catalyst (Pd/SiO2) by adding alkali metal potassium (K). A formidable promotion effect was observed when the K doping to Pd/SiO2 catalysts. It achieves a conversion rate of 93% for 270 ppmV of HCHO to harmless CO2 and H2O at a weight hourly space velocity (WHSV) of 300,000 mL/(g·hr) at 25°C. Multiple characterization results illustrated that a strong interaction between added K and Pd species was formed after K addition, which not only stabilized Pd species on the carrier surface but also markedly enhanced its dispersal on the SiO2 carrier. The increasing Pd dispersion induced more oxygen vacancies on the surfaces of the Pd/SiO2 catalysts. The formation of these oxygen vacancies can be attributed to the phenomenon of hydrogen spillover, which also contributed to elevating the electron density on the Pd sites. Meanwhile, the oxygen vacancies favored the O2 activation to form more reactive oxygen species participating in the HCHO oxidation reaction, thus improving the performance of Pd/SiO2 catalysts displayed for HCHO oxidation. This study provides a simple strategy to design high-performance irreducible carriers supported noble metal catalysts for HCHO catalytic oxidation.

Extraordinary synergy on 3D hierarchical porous Co-Cu nanocomposite for catalytic elimination of VOCs at low temperature and high space velocity

It is still a challenge to develop hierarchically nanostructured catalysts with simple approaches to enhance the low-temperature catalytic activity. Herein, a set of mesoporous Co-Cu binary metal oxides with different morphologies were successfully prepared via a facile ammonium bicarbonate precipitation method without any templates or surfactants, which were further applied for catalytic removal of carcinogenic toluene. Among the catalysts with different ratios, the CoCu0.2 composite oxide presented the best performance, where the temperature required for 90% conversion of toluene was only 237°C at the high weight hour space velocity (WHSV) of 240,000 mL/(gcat·hr). Meanwhile, compared to the related Co-Cu composite oxides prepared by using different precipitants (NaOH and H2C2O4), the NH4HCO3-derived CoCu0.2 sample exhibited better catalytic efficiency in toluene oxidation, while the T90 were 22 and 28°C lower than those samples prepared by NaOH and H2C2O4 routes, respectively. Based on various characterizations, it could be deduced that the excellent performance was related to the small crystal size (6.7 nm), large specific surface area (77.0 m2/g), hollow hierarchical nanostructure with abundant high valence Co ions and adsorbed oxygen species. In situ DRIFTS further revealed that the possible reaction pathway for the toluene oxidation over CoCu0.2 catalyst followed the route of absorbed toluene → benzyl alcohol → benzaldehyde → benzoic acid → carbonate → CO2 and H2O. In addition, CoCu0.2 sample could keep stable with long-time operation and occur little inactivation under humid condition (5 vol.% water), which revealed that the NH4HCO3-derived CoCu0.2 nanocatalyst possessed great potential in industrial applications for VOCs abatement.

Enhanced production of naphtha-range compounds from arundo donax via catalytic fast pyrolysis using SAPO-11

Arundo donax, acknowledged for its elevated energy content, substantial biomass yield and rapid growth, stands as an alluring candidate for biofuel production. In this investigation, a molecular sieve-based catalyst was utilized to scrutinize the catalytic fast pyrolysis (CFP) of Arundo donax, aiming for the production of naphtha-range compounds. The study also encompassed the evaluation of pyrolysis product yields within a fixed-bed reactor. The systematic exploration included an assessment of the impacts arising from catalyst type, temperature, weight hourly space velocity (WHSV), and N2 flow rate. The results demonstrated that at 500 °C, WHSV of 1 h−1 and N2 flow rate of 300 ml/min, SAPO-11 exhibited a selectivity of 64.55% to naphtha-range compounds and 64.55% to isomerous naphtha-range compounds. This was in stark contrast to the control group, which contained no catalyst (with a selectivity of 41.40% and 3.19%, respectively), SAPO-41 (with a selectivity of 11.02% and 9.55%, respectively) and HZSM-5 (with a selectivity of 59.89% and 53.51%, respectively). Additionally, SAPO-11 yielded the highest bio-oil compared to other catalysts (SAPO-11 of 28.52 wt% > none of 19.48 wt% > HZSM-5 of 18.90 wt% > SAPO-41 of 13.11 wt%). The conclusions drawn from these findings imply that the synthesized SAPO-11 catalyst exhibited superior catalytic activity and isomerization proficiency in contrast to other catalysts (SAPO-41 and HZSM-5). Remarkably, under the specified conditions of SAPO-11 catalyst, temperature = 500 °C, WHSV = 1 h−1 and N2 flow rate = 200 ml/min, the CFP process yielded a remarkable maximum absolute yield of the naphtha-range compound at 25.82 wt%, with an isomerized naphtha-range compound absolute yield of 25.35 wt%.

Space-confined manganese oxides nanosheets for efficient catalytic decomposition of ozone

Ground-level ozone has long posed a substantial menace to human well-being and the ecological milieu. The widely reported manganese-based catalysts for ozone decomposition still facing the persisting issues encompass inefficiency and instability. To surmount these challenges, we developed a mesoporous silica thin films with perpendicular nanochannels (SBA(⊥)) confined Mn3O4 catalyst (Mn3O4@SBA(⊥)). Under a weight hourly space velocity (WHSV) of 500,000 mL g−1 h−1, the Mn3O4@SBA(⊥) catalyst exhibited 100% ozone decomposition efficiency in 5 h and stability across a wide humidity range, which exceed the performance of bulk Mn3O4 and Mn3O4 confine in commonly reported SBA-15. Rapidly decompose 20 ppm O3 to a safety level below 100 μg m−3 in the presence of dust in smog chamber (60 × 60 × 60 cm) was also realized. This prominent catalytic performance can be attributed to the unique confined structure engenders the highly exposed active sites, facilitate the reactant-active sites contact and impeded the water accumulation on the active sites. This work offers new insights into the design of confined structure catalysts for air purification.