High Initial Activity Research Articles

A high-performance and anti-sulfur poisoning oxygen reduction reaction catalysts derive from molybdenum-doping on PtCo alloy nanoparticles surface

During the operation of fuel cell vehicles, sulfur dioxide (SO2) as a primary air pollutant can be transported to the cathode of the fuel cell with the air, leading to poisoning of the cathodic Pt-based catalyst, and subsequently, causing performance degradation and even shutdown. Therefore, there is an urgent need for SO2-tolerant Pt-based catalysts to mitigate poisoning in the cathodic oxygen reduction reaction (ORR). Herein, we report a carbon-supported Mo doped PtCo alloy catalyst with high-performance and anti-sulfur poisoning, termed as Mo-PtCo/C. Detailed investigations demonstrate that the Co in PtCo alloy nanoparticles (NPs) greatly promote ORR activity but do little to improve the SO2-tolerance. However, the PtCo alloy NPs doped with Mo not only exhibit a higher ORR activity, but also a superior SO2 poisoning resistance and a superior recovery performance. The optimal Mo-PtCo/C catalyst demonstrates a high initial mass activity of 871.0 mA mgPt−1, which is higher than that of the PtCo/C catalyst (initial value=558.8 mA mgPt−1) and 6.6 times higher than that of the commercial Pt/C (20 wt.% Pt, initial value=174.6 mA mgPt−1), along with a low mass activity loss of 36.19% after SO2 poisoning, which is much lower than 82.4% of the PtCo/C catalyst and 81.3% of the commercial Pt/C. More importantly, it is revealed that MoO3 formed on the PtCo NPs surface after Mo doping helps to reduce the electrooxidation potentials of SO2 to the operating potential of the fuel cell, thereby markedly boosting SO2-tolerance. Furthermore, the fuel cells test also confirmed that MoO3 improved the SO2-tolerance of the Mo-PtCo/C catalysts.

Bifunctional Zinc-Molybdate or Zinc molybdenum Oxide/Metal-Nitrogen-Carbon catalytic layers with improved four-electron selectivity for oxygen reduction in acidic medium

Platinum-group-metal-free metal-nitrogen-carbon catalysts for the oxygen reduction reaction have demonstrated high initial activity and power performance in proton exchange membrane fuel cells. The main challenge facing this class of catalysts is their poor durability in operating acidic fuel cells. Their key operando degradation mechanisms involve oxidative attacks triggered by the catalysis of the oxygen reduction on atomically-dispersed 3d transition metals. Reactive oxygen species such as H2O2 or radical species are particularly aggressive to the carbon matrix. Minimizing H2O2 by-product formation during oxygen reduction or actively scavenging any formed H2O2 are therefore promising routes to improve their durability.Here, we report that Zn-molybdate and Zn molybdenum oxide have low activity towards H2O2 decomposition and electro-reduction in acid, but result in a strong synergistic effect with various M-N-C catalysts. The addition of α-ZnMoO4 or Zn3(OH)2(MoO4)2 in cathode layers resulted in improved four-electron ORR selectivity of M-N-C catalysts (M = Fe, Co, Cr) as well as moderately improved durability in accelerated stress tests in O2-saturated pH 1 electrolyte. The improvement in selectivity could be rationalized by hydrogen peroxide electro-reduction measurements and catalase enzyme-like activity tests. Both types of measurements revealed higher reactivity towards H2O2 scavenging when Metal-N-C catalysts are physically mixed (in a catalytic layer) or together in a suspension in solution with Zn-molybdate or Zn molybdenum oxide, revealing a synergy effect. Control experiments with ZnCl2 and Na2MoO4 salts however suggest that leached ions from ZnMoO4 in acidic solution are likely at the root of the synergy effect.

Physiological adjustment effect of visual stimulation by fresh rose flowers on sympathetic nervous activity.

As modern societies are often stressful due to urbanization and artificialization, the physiological relaxing effects of natural environments or nature-derived stimuli on humans have attracted attention and scientific data are being accumulated. It is known that there is inter-individual variation in these effects. The study aim was to apply the law of initial values to investigate the physiological adjustment effect of viewing fresh roses on sympathetic nervous activity. In this crossover study, a total of 214 high school students, office workers, healthcare workers, and elderly people were analyzed. The participants viewed fresh roses in a vase for 4 min. In the control condition, participants did not view any fresh roses during the period. To offset any order effect, participants received visual stimuli in the order of fresh roses then the control (no fresh roses) or the control and then fresh roses. ln (LF/HF) of heart rate variability (HRV) obtained from a-a interval measurements using an acceleration plethysmograph and used as an index of sympathetic nervous activity. The initial value was ln (LF/HF) of HRV during the control viewing (no fresh roses), and the change value was ln(LF/HF) of HRV during visual stimulation by fresh roses minus the control viewing. The correlation between the two was assessed by determining Pearson's correlation coefficient r, which was significantly negative. A physiological adjustment effect was observed such that participants with high initial sympathetic nervous activity showed a decrease in activity after visual stimulation with fresh roses, whereas participants with low initial activity showed an increase.

The electronic medical record management systems may improve monitoring and control of disease activity in patients with ankylosing spondylitis

To investigate the impact of an electronic medical record management system (EMRMS) on disease activity and the frequency of outpatient visits among patients with ankylosing spondylitis (AS). We identified 652 patients with AS who were followed up for at least 1 year before and after the first Ankylosing Spondylitis Disease Activity Score (ASDAS) assessment and compared the number of outpatient visits and average visit time within 1 year before and after the initial ASDAS assessment. Finally, we analyzed 201 patients with AS who had complete data and received ≥ 3 continuous ASDAS assessments at an interval of 3 months, and we compared the results of the second and third ASDAS assessments with those of the first. The number of annual outpatient visits increased after ASDAS assessment (4.0 (4.0, 7.0) vs. 4.0 (4.0, 8.0), p < 0.001), particularly among those with a high initial disease activity. The average visit time was reduced within 1 year after ASDAS assessment (6.4 (8.5, 11.2) vs. 6.3 (8.3, 10.8) min, p = 0.073), especially among patients whose with an inactive disease activity was < 1.3 (ASDAS C-reactive protein (CRP) 6.7 (8.8, 11.1) vs. 6.1 (8.0, 10.3) min, p = 0.033; ASDAS erythrocyte sedimentation rate (ESR) 6.4 (8.7, 11.1) vs. 6.1 (8.1, 10.0) min, p = 0.027). Among patients who received at least three ASDAS assessments, the third ASDAS-CRP tended to be lower than the first (1.5 (0.9, 2.1) vs. 1.4 (0.8, 1.9), p = 0.058). The use of an EMRMS increased the frequency of ambulatory visits among AS patients with high and very high disease activity and reduced the visit time among those with an inactive disease. Continual ASDAS assessments may help control the disease activity of patients with AS.

Improving the Coke Resistance of Ni-Ceria Catalysts for Partial Oxidation of Methane to Syngas: Experimental and Computational Study.

The synthesis of syngas (H2 : CO=2) via catalytic partial oxidation of methane (CPOM) is studied over noble metal doped Ni-CeO2 bimetallic catalysts for CPOM reaction. The catalysts were synthesized via a controlled deposition approach and were characterized using XRD, BET-surface area analysis, H2 -TPR, TEM, Raman and TGA analysis. The catalysts were experimentally and computationally studied for their activity, selectivity, and long-term stability. Although the pure 5Ni/CeO2 catalyst showed high initial activity (∼90%) of CH4 conversion, it rapidly deactivates around 20% of its initial activity within 140 hours of TOS. Doping of Ni/CeO2 catalyst with noble metal was found to be coke resistant with the best-performing Ni-Pt/CeO2 catalyst showed ∼95% methane conversion with >90% selectivity at a temperature of 800 °C, having exceptional stability for about 300 hours of time-on-stream (TOS). DFT studies were performed to calculate the activation barrier for the C-H activation of methane over the Ni, Ni3 Pt, Ni3 Pd, and Ni3 Ru (111) surfaces showed nearly equal activation energy over all the studied surfaces. DFT studies showed high coke formation tendency of the pure Ni (111) having a very small C-C coupling activation barrier (14.2 kJ/mol). In contrast, the Ni3 Pt, Ni3 Pd, and Ni3 Ru (111) surfaces show appreciably higher C-C coupling activation barrier (∼70 kJ/mol) and hence are more resistant against coke formation as observed in the experiments. The combined experimental and DFT study showed Ni-Pt/CeO2 as a promising CPOM catalyst for producing syngas with high conversion, selectivity and long-term stability suited for future industrial applications.

Effect of MoO3 on Pd nanoparticles for efficient formic acid electrooxidation

Palladium is a promising formic acid electro-oxidation (FAO) catalyst due to its higher initial activity than platinum. However, suffering from the adsorption of hydrogen and CO-like species, the activity and stability of Pd are still unsatisfied. Herein, palladium nanoparticles deposited on carbon supported molybdenum trioxide (Pd–MoO3/C) is prepared with MoO3 as the promoter for FAO. X-ray photoelectron spectroscopy analysis proves the close contact between Pd and MoO3, which generates the hydrogen spillover effect and forms the Pd–Mo structure. The hydrogen spillover effect enhances the desorption of hydrogen from Pd and facilitates the FAO activity. Both the spillover effect and Pd–Mo structure contribute to the removal of COad and facilitate the durability and anti-CO poisoning ability of the catalyst. With the optimized ratio of MoO3 to carbon black, the Pd–MoO3/C-20 catalyst owns the best specific activity of 5.86 mA cm−2, which is 1.86 times of Pd/C.

Two-dimensional MXenes as catalytic “flying carpets” to transport biomass valorization towards new horizons: The case of furfural catalytic transfer hydrogenation over noble-metal free niobium-based carbides

The reductive conversion of biomass-derived furfural through catalytic transfer hydrogenation (CTH) over non-precious metal catalysts is regarded as a promising strategy to successfully implement the biorefinery concept. Here, we show that two-dimensional niobium carbides (MXenes) efficiently catalyze the liquid-phase CTH of furfural in the presence of 2-propanol as hydrogen donor. At 160 °C Nb2CTx and Nb4C3Tx showed remarkable initial activity values (130 and 73 h−1, respectively), exceeding the one of pure Nb2O5 (21 h−1) by factor of 6.2 and 3.5. A targeted surface characterization by acid site titrations and X-ray photoelectron spectroscopy allowed to correlate the catalytic behavior with the acidic features and the peculiar surface chemistry of Nb-MXenes species. The presence of strong acid sites in Nb2CTx was associated to high initial activity, but also to a pronounced tendency to undergo deactivation. Differently, Nb4C3Tx, despite the lower initial activity, assured 70 % of furfural conversion after 8 h and it showed good stability over six runs. This study could bring new opportunities for the rational design of advanced noble metal-free catalysts with enhanced activity for biomass valorization.

The properties and health hazards from early nuclear weapon fallout: The Castle Bravo incident revisited

Early fallout is defined as the fallback to the earth’s surface of radioactive particles shortly after a nuclear detonation (often arbitrarily defined within 24 h). At the difference of wide spreading global fallout, early fallout mainly consists of larger particles that are often visible. The initial mixture is rich in short- and very short-lived radionuclides associated with a very high initial activity that decreases rapidly (in 7 h, the dose rate is reduced by 90%). The main danger of early fallout results from external irradiation by highly penetrating gamma-radiation that may cause acute radiation sickness. Only in the case of the thyroid, internal irradiation by the incorporation of radioiodine may prevail. The bombings of Hiroshima and Nagasaki are examples of airbursts with many fatalities by prompt effects (blast, burns, and initial ionizing radiations), but they produced little fallout. The nuclear test code-named Castle Bravo on the Marshall Islands (1954) did not have casualties by its blast, thermal or initial radiation effects, but the inhabitants of the nearby islands and the crew of a Japanese fisherboat (Lucky Dragon) were affected by large amounts of fallout. For the inhabitants of the Rongelap Atoll, the average dose from external irradiation was assessed at 1.6 Gy. From a clinical point of view, based on hematological data using the METREPOL classification system, the acute radiation syndrome can be categorized as mild (H1). Blood transfusions were not required, and antibiotics were not administered for prophylaxis or therapy of infections related to irradiation. The equivalent dose received by the thyroid resulted mainly from internal irradiation with 7.6 Gy. The major late effects were thyroid abnormalities, including thyroid failure, nodules, and malignant tumors. The 23 Japanese crewmen seem to have been irradiated by higher doses (2.9 Gy). Compared to the hematological data of the Rongelap victims, the evolution pattern over time is quite similar. Still, the absolute values of the cell counts are lower, and on average, the acute radiation syndrome can be categorized as rather moderate (H2). Considering the individual cases, data show a large interindividual variability, and the clinical severity category ranges from “no alterations” (H0) to severe (H3). Victims were treated with repeated blood transfusions and antibiotics. Several of them developed jaundice, and one of them died six months after the incident showing symptoms compatible with subacute liver failure. A radiochemical organ analysis revealed that only the bones were clearly contaminated with fission products. In the 1990s, many surviving crewmen were diagnosed with hepatitis C, incurred probably from blood transfusions that were often contaminated at the time, and died from hepatocellular carcinomas. Thyroid dysfunctions were not reported. The Castle Bravo case permits to study the health hazards resulting from early fallout independently from the prompt effects of a nuclear detonation. The prevailing external irradiation was confirmed, except for the thyroid with a higher dose resulting from radioiodine incorporation mainly caused by ingestion. As shown for the Japanese fishermen, the risks incurred by medical treatments must be carefully weighed against the benefits of the therapeutic intervention. The cause of death of the only short-term fatality is not fully elucidated, but is consistent with liver failure due to transfusion hepatitis rather than radiation effects.

Human osteoblasts response to different dental implant abutment materials: An in-vitro study

ObjectivesThis study aimed to investigate human osteoblasts (HOB) response towards different dental implant abutment materials. MethodsFive dental implant abutment materials were investigated: (1) titanium (Ti), (2) titanium coated nitride (TiN), (3) cobalt chromium (CoCr), (4) zirconia (ZrO₂), and (5) modified polyether ether ketone (m-PEEK). HOBs were cultured, expanded, and seeded according to the supplier’s protocol (PromoCell, UK). Cell proliferation and cytotoxicity were evaluated at days 1, 3, 5, and 10 using Alamar Blue (alamarBlue) and lactate dehydrogenase (LDH) colorimetric assays. Data were analysed via two-way ANOVA, one-way ANOVA and Tukey’s post hoc test (significance was determined as p < 0.05 for all tests). ResultsAll the investigated materials showed high and comparable initial proliferation activities apart from ZrO₂ (46.92%), with P% of 79.91%, 68.77%, 73.20%, and 65.46% for Ti, TiN, CoCr, and m-PEEK, respectively. At day 10, all materials exhibited comparable and lower P% than day 1 apart from TiN (70.90%) with P% of 30.22%, 40.64%, 37.27%, and 50.65% for Ti, CoCr, ZrO₂, and m-PEEK, respectively. The cytotoxic effect of the investigated materials was generally low throughout the whole experiment. At day 10, the cytotoxicity % was 7.63%, 0.21%, 13.30%, 5.32%, 8.60% for Ti, TiN, CoCr, ZrO₂, and m-PEEK. The Two-way ANOVA and Tukey’s Multiple Comparison Method highlighted significant material and time effects on cell proliferation and cytotoxicity, and a significant interaction (p < 0.0001) between the tested materials. Notably, TiN and m-PEEK showed improved HOB proliferation activity and cytotoxic levels than the other investigated materials. In addition, a non-significant negative correlation between viability and cytotoxicity was found for all tested materials. Ti (p = 0.07), TiN (p = 0.28), CoCr (p = 0.15), ZrO₂ (p = 0.17), and m-PEEK (p = 0.12). SignificanceAll the investigated materials showed excellent biocompatibility properties with more promising results for the newly introduced TiN and m-PEEK as alternatives to the traditionally used dental implant and abutment materials.

How has the disease course of pediatric ulcerative colitis changed throughout the biologics era? A comparison with the IBSEN study.

BACKGROUNDIn Korea, infliximab was approved for use in children with ulcerative colitis (UC) in October 2012. AIMTo compare the clinical course of UC before and after the introduction of biological agents, and to compare with the IBSEN study. METHODSPatients under 18 years of age, who were diagnosed with UC and followed from January 2003 to October 2020, were included in the study. Group A (n = 48) was followed for at least 2 years between January 2003 and October 2012, and Group B (n = 62) was followed for at least 2 years between November 2012 and October 2020. We compared endoscopic remission, drug composition, relapse rate, steroid-free period, and the quality of life of each group. We plotted the clinical course of the included patients using the pediatric UC activity index score, and compared our patients with those in the IBSEN study. RESULTSAfter 2 years of treatment, colonoscopy evaluation revealed different outcomes in the two treatment groups. Remission was confirmed in 14 patients (29.2%) of Group A, and in 31 patients (50.0%) of Group B (P < 0.012). The median cumulative corticosteroid-free period was 3.0 years in Group A and 4.4 years in Group B. Steroid-free period of Group B was significantly longer than that of Group A (P < 0.001). There was a statistically significant difference between the two groups in evaluation of the relapse rate during the observation period (P < 0.001). The plotted clinical course graphs of Group A showed similar proportions to the graphs in the IBSEN study. However, in Group B, the proportion of patients corresponding to curve 1 (remission or mild severity after initial high activity) was high at 76% (47/62). CONCLUSIONThe incidence of relapse has decreased and the steroid-free period has increased after the introduction of the biological agent. The clinical course also showed a different pattern from that of IBSEN study. The active use of biological agents may change the long-term disease course in moderate to severe pediatric UC.

Antifungal efficacy of Hyptis suaveolens and Rumex nepalensis extracts against Alternaria solani: An approach for bio-pesticides

Globally, early blight is one of the serious threats leading to significant reduction of potato yield. The use of plant extracts in the management of plant diseases is gaining global significance. Hence, the main objective of this study was to determine the antifungal activity of Rumex nepalensis and Hyptis suaveolens (L.) Poiteau extracts against the fungal pathogen (Alternaria solani) causing early blight in potato. The study employed experimental research method with completely randomized design wherein the plant extracts were tested against the pathogen through in vitro and in vivo studies. In the in vitro study, results from the poison food technique showed that the aqueous extracts of aerial parts of R.nepalensis (RnA) was the most efficient in reducing the diameter growth of the fungus than R.nepalensis roots (RnR) and H. suaveolens (HS). The efficacy of the extracts was in the decreasing order of RnA > RnR > HS at all concentrations (20%, 40% and 60%). The fungal biomass extraction showed similar trend with RnA having the highest Initial Activity on Biomass (IAB) followed by RnR and HS. Interestingly, the fungal biomass growth decreased with increase in concentration of all three extracts. In the in vivo technique, plants treated with RnA prior to infection exhibited better tolerance to the test pathogen. Comparatively, RnA showed less Disease Severity Index (DSI) than RnR and HS for both preventive and curative controls. Consequently, the percentage reduction of disease was recorded highest in RnA preventive control (71.43%) compared to other treatments. The preventive control showed lower DSI and higher reduction of disease compared to the curative control. Although all three extracts showed some degree of antifungal activity against Alternaria solani, RnA showed higher activity in both in vitro and in vivo treatments. Therefore, RnA extracts can be used as a potential bio-fungicide for the control of early blight in potato.

Searching for New Genetic Biomarkers of Axial Spondyloarthritis.

Background: Axial spondyloarthritis (axSpA) is a chronic inflammatory condition of the spine. In addition to musculoskeletal symptoms, there are also extra-articular manifestations. The aim of this study was to search for new biomarkers associated with the clinical presentation and treatment response in axSpA patients. Methods: In this study, 106 axSpA patients and 110 healthy controls were enrolled. Six single-nucleotide polymorphisms (SNPs) were selected for genotyping: ERAP1 rs2287987, ERAP2 rs2549782, TNF rs1800629, TNFRSF1A rs767455, TNFRSF1B rs1061622, and FCGR2A rs1801274. Participants were examined at baseline and after 12 and 24 weeks of anti-TNF therapy. Results: SNPs associated with high axSpA initial activity were TNFRSF1A rs767455 and TNFRSF1B rs1061622 (p < 0.008). The ERAP1 rs2287987 AA genotype was more frequently observed in patients with enthesitis (AA vs. G+, p = 0.049), while the TNFRSF1B rs1061622 GG genotype was more common in participants with uveitis (GG vs. TT, p = 0.042). Potential in predicting anti-TNF treatment response was demonstrated by ERAP1 rs2287987, ERAP2 rs2549782, TNFRSF1B rs1061622, and FCGR2A rs1801274. Conclusions: SNPs can be used to identify patients at risk of severe disease to initiate treatment earlier. Genetic testing will allow clinicians to choose the right drug for the patient.

Protrusions induction by carbon black on surface of activated carbon to enhance its catalytic activity

Catalytic methane decomposition is considered as a promising hydrogen production technology without CO2 emission. Catalyst is generally required to reduce reaction temperature, among which, carbon-based catalysts are widely studied due to their excellent catalytic performance and low cost. Activated carbon (AC), although presents high initial activity, suffers from fast deactivation; In comparison, carbon black (CB) shows low activity but good stability, and its catalytic performance maintains ability inspires a novel method for AC optimization. According to the physical property difference of AC and CB, a novel catalyst is prepared by doping CB on the surface and in the pores of AC. And surface property modified by HNO3 is also recommended, because the increase of functional groups further improves the adsorption performance. The results illustrate that ACN + BP2000-20:3 show advantages in hydrogen yield, weight increase velocity and carbon yield. Meanwhile, not only the initial activity is improved by a large margin, but also the deactivation time is progressively prolonged. The analysis results show that CB loading significantly increased the number of micropores, which is the key factor for the high initial catalytic activity. And the protrusion, induced by CB, are characterized by unique graphene edges defect, which provides active sites and furtherly promotes the reaction.

Hydrogenolysis of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran Over a Modified CoAl-Hydrotalcite Catalyst.

The catalytic hydrogenolysis of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) is a promising route towards sustainable liquid fuels with a high energy density. Herein, a novel CuCoNiAl-containing mixed metal oxide catalyst (CuCoNiAl-MMO) was prepared by calcination a layered double hydroxide (LDH) precursor in N2 at 500 °C, then applied for the catalytic hydrogenolysis of HMF to DMF. The effects of reaction time, reaction temperature and hydrogen pressure on DMF selectivity were investigated. Under relatively mild reaction conditions (180°C, 1.0 MPa H2, 6.0 h), CuCoNiAl-MMO showed both a high initial activity and selectivity for hydrogenolysis of HMF to DMF, with HMF conversion rate of 99.8% and DMF selectivity of 95.3%. Catalysts characterization studies using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) revealed the presence of various metal oxides and metallic copper on the surface of the CuCoNiAl-MMO catalyst, with the presence of mixed metal-oxide-supported metallic Cu nanoparticles being responsible good hydrogenolysis activity of the catalyst for selective DMF synthesis.

Predictors of response to TNF inhibitors in rheumatoid arthritis: an individual patient data pooled analysis of randomised controlled trials

ObjectiveTo identify patient characteristics associated with responsiveness to tumour necrosis factor inhibitors (TNFi) in rheumatoid arthritis (RA).Materials and methodsIndividual patient data from 29 randomised controlled trials (RCTs) evaluating the efficacy...

The Effect of Different Promoters (La2O3, CeO2, and ZrO2) on the Catalytic Activity of the Modified Vermiculite-Based Bimetallic NiCu/EXVTM-SiO2 Catalyst in Methane Dry Reforming.

An X-NiCu/EXVTM-SiO2 (X = La, Ce, and Zr) catalyst was successfully prepared by using modified vermiculite as a support by the impregnation method. This experiment investigated the effects of La2O3, CeO2, and ZrO2 promoters on the activity of the NiCu/EXVTM-SiO2 catalyst. The study found that the addition of three different metal oxides did not improve the activity of the NiCu/EXVTM-SiO2 catalyst. On the contrary, some Ni active sites were covered by the promoter, which reduced the number of active sites, resulting in its catalytic activity lower than NiCu/EXVTM-SiO2. In addition, the promoted catalysts that were repeatedly calcined two times can significantly reduce the textural property as well as active sites of the catalyst, resulting in the lower activity. However, in X-NiCu/EXVTM-SiO2, Ce-NiCu/EXVTM-SiO2 showed relatively high initial catalytic activity, with the initial conversion rate of CH4 reaching 60.1% and the initial conversion rate of CO2 reaching 89.1%. This is mainly because the catalyst has a stronger basic site on the surface to facilitate the adsorption of CO2 molecules, and the smaller metal particle size is also conducive to the cleavage of C–H bonds.

KCl Extracted from Chlorine Bypass Dust as Activator for Plain Concrete.

This study demonstrated the use of KCl separated from chlorine bypass dust (CBD) as an activator for plain concrete. The separated KCl was mixed with either ground granulated blast-furnace slag (BFS) alone, or a mixture of BFS and cement. The mixed paste of separated KCl and BFS set within 24 h, and exhibited a compressive strength of 22.6 MPa after 28 d. The separated KCl, cement, and BFS mixture exhibited a more rapid setting and a higher initial activity. Further, the compressive strength at 28 d was 57.7 MPa, which was 26.2% higher than that of the mixture without the activator. Water curing of samples with added separated KCl led to the generation of hydrocalumite, or Friedel’s salt. However, this hydrocalumite was decomposed while being cured under autoclave conditions at 180 °C. Overall, KCl was an effective activator for composite materials containing cement, and resulted in superior properties compared to mineral admixtures without an activator.

Deactivation Mechanism of Palladium Catalysts for Ethanol\t\t\tConversion to Butanol

A Pd/Al2O3 catalyst (Pd = 0.1 wt\t\t\t\t\t%) for ethanol conversion to butanol deactivates within 10 h of service, despite\t\t\t\t\tits high initial activity at 275°C. Probable deactivation mechanisms were\t\t\t\t\texplored, including poisoning of\t\t\t\t\t\tPd/Al2O3 due to adsorption of\t\t\t\t\tby-products on Pd, sintering of Pd phases, leaching of Pd from the catalyst,\t\t\t\t\tchanges in the Pd electronic state, changes in the catalyst’s porous structure,\t\t\t\t\tand blockage of Al2O3 active\t\t\t\t\tsites. The Pd/Al2O3 deactivation\t\t\t\t\twas found to be mainly caused by CO molecules that evolved during side\t\t\t\t\treactions. These molecules can either block Pd active sites due to the formation\t\t\t\t\tof strong Pd–CO complexes, or enter a CO disproportionation reaction to form\t\t\t\t\tcarbon deposits on Pd phases. The knowledge gained from this study can be used\t\t\t\t\tfor the targeted modification of\t\t\t\t\t\tPd/Al2O3 and the creation of\t\t\t\t\tselective systems operating stably in the presence of by-products.

Key factors that affect catalytic activity of activated carbon-based catalyst in chemical looping methane decomposition for H2 production

Chemical looping methane decomposition for hydrogen production is widely discussed, and activated carbon (AC) is widely studied as a cheap, easily-available catalyst with high initial activity. In this study, 10%, 30% and 50% HNO3 was used to treat AC to change its specific surface area, pore structure, and surface functional groups. After reactions at 900 °C and 950 °C, the AC is characterized and analyzed, and key factors affecting its catalytic performance are assessed. After acid treatment, the specific surface areas and pore volumes of AC are decreased, the number of oxygen-containing and nitrogen-containing functional groups is increased. It may be expected that increases of functional groups would increase the number of active surface sites, however, experiments have shown surface areas and pore volumes are representative and perhaps linearly correlated with methane conversions. The decreases in surface areas and pore volumes are predominantly associated with the elimination of micropores. Simultaneously, conclusions from molecular simulations are that smaller pore sizes in AC promotes adsorption of methane molecules on the AC and their conversion to hydrogen. Therefore, the unfavorable influences of decreased specific surface area and changed pore structure are detrimental to the initial steps of methane adsorption and then decomposition.

Preparation of cigarette butts/coal‐based porous carbon and its catalytic methane decomposition to hydrogen

AbstractA new type of cigarette butts/coal‐based composite porous carbon was prepared by potassium hydroxide chemical activation method and used for methane decomposition to hydrogen. The effects of mass mixing ratio of the used cigarette butts/coal and carbonization temperature on the surface properties and structure of carbon materials were studied. The results show that the optimal mass mixing ratio of cigarette butts/coal is 1:3, and the increase in temperature can promote the specific surface area of carbon materials from 1850 to 2785 m2/g, the distribution of pore size is also changed from a large number of micropores to mesopores, and the structure became more disordered. DT/YT‐3‐1023 has the highest initial activity, DT/YT‐3‐1123 has the highest stability, and a certain amount of carbon fibers are deposited on the surface of carbon materials after the reaction.