The negative effect of P addition of La/HZSM-5 on the catalytic performance in methyl mercaptan abatement

Acidic oil, which is easily obtained and with lower cost, is a potential raw material for biodiesel production. Apart from containing large quantity of FFAs (free fatty acids), acidic oil usually contains some amount of inorganic acid, glycerides and some other complex components, leading to complicated effect on lipase’s catalytic performance. Exploring the efficient process of converting acidic oil for biodiesel production is of great significance to promote the use of acidic oil. A two-step conversion process for acidic soybean oil was proposed in this paper, where sulfuric acid-mediated hydrolysis was adopted first, then the hydrolyzed free fatty acid, collected from the upper oil layer was further subject to the second-step esterification catalyzed by immobilized lipase Novozym435. Through this novel process, the negative effect caused by harmful impurities and by-product glycerol on lipase was eliminated. A fatty acid methyl ester (FAME) yield of 95% could be obtained with the acid value decreased to 4 mgKOH/g from 188 mgKOH/g. There was no obvious loss in lipase’s activity and a FAME yield of 90% could be maintained with the lipase being repeatedly used for 10 batches. This process was found to have a good applicability to different acidic oils, indicating it has great prospect for converting low quality oil sources for biodiesel preparation.

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Effect of Fe Additives on the Catalytic Performance of Ion-Exchanged CsX Zeolites for Side-Chain Alkylation of Toluene with Methanol

Catalysts ◽

10.3390/catal9100829 ◽

2019 ◽

Vol 9 (10) ◽

pp. 829 ◽

Cited By ~ 4

Author(s):

Zhang ◽

Yuan ◽

Miao ◽

Li ◽

Shan ◽

...

Keyword(s):

Catalytic Activity ◽

Catalytic Performance ◽

High Yield ◽

Side Chain ◽

Impregnation Method ◽

Basic Sites ◽

Lewis Acidic Sites ◽

X Zeolite ◽

Acidic Sites ◽

Negative Effect

The side-chain alkylation of toluene with methanol was investigated over some Fe-modified Cs ion-exchanged X zeolite (CsX) catalysts prepared via the impregnation method using different iron sources. The absorption/activation behaviors of the reactants on the surface of the catalysts were studied by in situ Fourier-transform infrared (FT-IR) spectroscopy and temperature programmed desorption (TPD) mass measurements. Modification of CsX with a small amount of FeCl3 could result in a considerable decrease in catalytic activity, due mainly to the remarkable decrease in the density of acidic and basic sites of the catalysts. Interestingly, the Fe(NO3)3-modified CsX with an optimum Fe loading of 0.15 wt.% shows improved catalytic activity and high yield compared to the side-chain alkylation products. Modification of CsX with Fe(NO3)3 could also result in a decrease in basic sites of the catalyst. However, such a change does not bring an obvious negative effect on the adsorption/activation of toluene, while it could effectively inhibit the generation of the undesired bidentate formate. Furthermore, the introduced FeOx species (derived from the decomposition of Fe(NO3)3) may also act as new Lewis acidic sites to participate in the activation of methanol and to stabilize the formed active intermediates (i.e., unidentate formate). Therefore, modification of CsX with a suitable amount of Fe(NO3)3 may adjust its adsorption/activation ability for reagents by changing the acid–base properties of the catalyst, which can finally enhance the catalytic performance for the side-chain alkylation of toluene with methanol.

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Positive effect of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on homogeneous photocatalytic reduction of CO2

Chemical Communications ◽

10.1039/c7cc08927a ◽

2018 ◽

Vol 54 (27) ◽

pp. 3323-3326 ◽

Cited By ~ 4

Author(s):

Markus Pschenitza ◽

Simon Meister ◽

Bernhard Rieger

Keyword(s):

Electron Donor ◽

Catalytic Performance ◽

Photocatalytic Reduction ◽

Reduction Of Co2 ◽

P Addition ◽

Positive Effect

Addition of DBU enables reducing the amount of sacrificial electron donor and increases catalytic performance in photocatalytic CO2 reduction.

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Grazing effect of flagellates on bacteria in response to phosphate addition in the oligotrophic Cretan Sea, NE Mediterranean

FEMS Microbiology Ecology ◽

10.1093/femsec/fiaa086 ◽

2020 ◽

Vol 96 (6) ◽

Author(s):

Andreas Oikonomou ◽

Eleni Livanou ◽

Manolis Mandalakis ◽

Anna Lagaria ◽

Stella Psarra

Keyword(s):

Grazing Rate ◽

P Availability ◽

Pigment Analysis ◽

Planktonic Food ◽

Grazing Effect ◽

Bacterial Removal ◽

Negative Effect ◽

Ne Mediterranean ◽

P Addition ◽

Cretan Sea

ABSTRACT The planktonic food web in the oligotrophic Mediterranean Sea is dominated by small-sized (<20 μm) microbes, with nanoflagellates being the major bacterial grazers and the main participants in nutrient cycling. Phosphate is a key nutrient in the P-limited Cretan Sea (NE Mediterranean) and P-availability can affect its trophic dynamics. Here, we examined the grazing potential of heterotrophic (HF) and pigmented (PF) nanoflagellates as a response mechanism to phosphate amendment. Flagellate grazing effect on bacteria was quantified in P-amended nutrient-depleted water from the Cretan Sea over the course of 4 days using microcosm experiments. P-addition positively affected HF abundance, while PF abundance remained unchanged. At the community level, P-addition had a negative effect on PF bacterial removal rates. In the control, PF-grazing rate was significantly higher than that of HF throughout the experiment. Pigment analysis showed no changes in phytoplankton community composition as a result of P-addition, indicating that PF grazing rate declined as a physiological response of the cells. The present study emphasizes the dominant grazing role of PF under P-depleted conditions and reveals that during the late stratified season PF respond to P-addition by lowering their grazing rates, enhancing the relative importance of bacterial removal by HF.

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Removal of VOCs by Ozone: n-Alkane Oxidation under Mild Conditions

Catalysts ◽

10.3390/catal11040506 ◽

2021 ◽

Vol 11 (4) ◽

pp. 506

Author(s):

Alina I. Mytareva ◽

Igor S. Mashkovsky ◽

Sergey A. Kanaev ◽

Dmitriy A. Bokarev ◽

Galina N. Baeva ◽

...

Keyword(s):

Catalytic Oxidation ◽

Oxygen Vacancies ◽

Oxide Catalyst ◽

Catalytic Performance ◽

High Concentration ◽

Volatile Organic ◽

Negative Effect ◽

Manganese Oxide Catalyst ◽

Conventional Solution ◽

Al2o3 Catalyst

Volatile organic compounds (VOCs) have a negative effect on both humans and the environment; therefore, it is crucial to minimize their emission. The conventional solution is the catalytic oxidation of VOCs by air; however, in some cases this method requires relatively high temperatures. Thus, the oxidation of short-chain alkanes, which demonstrate the lowest reactivity among VOCs, starts at 250–350 °C. This research deals with the ozone catalytic oxidation (OZCO) of alkanes at temperatures as low as 25–200 °C using an alumina-supported manganese oxide catalyst. Our data demonstrate that oxidation can be significantly accelerated in the presence of a small amount of O3. In particular, it was found that n-C4H10 can be readily oxidized by an air/O3 mixture over the Mn/Al2O3 catalyst at temperatures as low as 25 °C. According to the characterization data (SEM-EDX, XRD, H2-TPR, and XPS) the superior catalytic performance of the Mn/Al2O3 catalyst in OZCO stems from a high concentration of Mn2O3 species and oxygen vacancies.

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Effects of rare-earth (Nd, Er and Y) doping on catalytic performance of HZSM-5 zeolite catalysts for methyl mercaptan (CH3SH) decomposition

Applied Catalysis A General ◽

10.1016/j.apcata.2017.01.011 ◽

2017 ◽

Vol 533 ◽

pp. 66-74 ◽

Cited By ~ 22

Author(s):

Dedong He ◽

Husheng Hao ◽

Dingkai Chen ◽

Jiangping Liu ◽

Jie Yu ◽

...

Keyword(s):

Rare Earth ◽

Catalytic Performance ◽

Zeolite Catalysts ◽

Methyl Mercaptan

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Promotion of catalytic performance by adding chromium into HZSM-5 zeolite catalyst for methyl mercaptan catalytic conversion

Materials Chemistry and Physics ◽

10.1016/j.matchemphys.2019.121952 ◽

2020 ◽

Vol 239 ◽

pp. 121952 ◽

Cited By ~ 1

Author(s):

Jie Yu ◽

Dedong He ◽

Yutong Zhao ◽

Jichang Lu ◽

Jiangping Liu ◽

...

Keyword(s):

Zeolite Catalyst ◽

Catalytic Conversion ◽

Catalytic Performance ◽

Methyl Mercaptan

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Comparative Study of the Efficiency of Different Noble Metals Supported on Hydroxyapatite in the Catalytic Lean Methane Oxidation under Realistic Conditions

Materials ◽

10.3390/ma14133612 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3612

Author(s):

Zouhair Boukha ◽

Beatriz de Rivas ◽

Juan R. González-Velasco ◽

José I. Gutiérrez-Ortiz ◽

Rubén López-Fonseca

Keyword(s):

Comparative Study ◽

Active Sites ◽

Noble Metals ◽

Nir Spectroscopy ◽

Catalytic Performance ◽

Ruthenium Catalysts ◽

Slow Process ◽

Inhibiting Effect ◽

Degree Of Oxidation ◽

Negative Effect

The combustion of lean methane was studied over palladium, rhodium, platinum, and ruthenium catalysts supported on hydroxyapatite (HAP). The samples were prepared by wetness impregnation and thoroughly characterized by BET, XRD, UV-Vis-NIR spectroscopy, H2-TPR, OSC, CO chemisorption, and TEM techniques. It was found that the Pd/HAP and Rh/HAP catalysts exhibited a higher activity compared with Pt/HAP and Ru/HAP samples. Thus, the degree of oxidation of the supported metal under the reaction mixture notably influenced its catalytic performance. Although Pd and Rh catalysts could be easily re-oxidized, the re-oxidation of Pt and Ru samples appeared to be a slow process, resulting in small amounts of metal oxide active sites. Feeding water and CO2 was found to have a negative effect, which was more pronounced in the presence of water, on the activity of Pd and Rh catalysts. However, the inhibiting effect of CO2 and H2O decreased by increasing the reaction temperature.

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Raw Biogas as Feedstock for the OCM Process

Catalysts ◽

10.3390/catal12010054 ◽

2022 ◽

Vol 12 (1) ◽

pp. 54

Author(s):

Barbara Michorczyk ◽

Jakub Sikora ◽

Bogusława Kordon-Łapczyńska ◽

Dorota Gaweł ◽

Izabela Czekaj

Keyword(s):

Photoelectron Spectroscopy ◽

Oxidative Coupling ◽

Methane Conversion ◽

Catalytic Performance ◽

Oxidative Coupling Of Methane ◽

Raw Material ◽

Plant Materials ◽

X Ray ◽

Poisoning Effect ◽

Negative Effect

The paper presents the research results obtained in the process of oxidative coupling of methane, in which unpurified biogas was used as the feedstock. Biogas obtained from two kinds of biomass materials, i.e., plant materials (potato and beet pulp, Corn-Cob-Mix—biogas 1) and animal waste (waste from fish filleting—biogas 2) was considered. The influence of temperature, the ratio of methane/oxygen and total flows of feedstock on the catalytic performance in oxidative coupling of methane process was investigated. Comparative tests were carried out using pure methane and a mixture of methane-carbon dioxide to simulate the composition of biogas 2. The process was carried out in the presence of an Mn-Na2WO4/SiO2 catalyst. Fresh and used catalysts were characterised by means of powder X-ray diffraction, X-ray photoelectron spectroscopy, and low-temperature nitrogen adsorption techniques. In oxidative coupling of methane, the type of raw material used as the source of methane has a small effect on methane conversion (the differences in methane conversion are below 3%), but a significant effect on the selectivity to C2. Depending on the type of raw material, the differences in selectivity to C2 reach as high as 9%. However, the Mn-Na2WO4/SiO2 catalyst operated steadily in the tested period of time at any feedstock composition. Moreover, it was found that CO2, which is the second main component of biogas in addition to methane, has an effect on catalytic performance. Comparative results of catalytic tests indicate that the CO2 effect varies with temperature. Below 1073 K, CO2 exerts a small poisoning effect on methane conversion, while above this temperature the negative effect of CO2 disappears. In the case of selectivity to C2+, the negative effect of CO2 was observed only at 1023 K. At higher temperatures, CO2 enhances selectivity to C2+. The effect of CO2 was established by correlating the catalytic results with the temperature programmed desorption of CO2 investigation. The poisoning effect of CO2 was connected with the formation of surface Na2CO3, whose concentration depends on temperature.

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Effect of Competitive Adsorbates on the Catalytic Activity of H3PMo12O40@C in the Oxidation of NMST to NMSBA

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2019-0154 ◽

2020 ◽

Vol 18 (3) ◽

Author(s):

Hua-jie Liu ◽

Zhou-wen Fang ◽

Xin-zhi Zhou ◽

Xiang-li Long

Keyword(s):

Acetic Acid ◽

Catalytic Activity ◽

Competitive Adsorption ◽

Phosphomolybdic Acid ◽

Catalytic Performance ◽

Good Dispersion ◽

Tem Characterization ◽

Negative Effect ◽

Impregnation Solution

AbstractThe effect of competitive adsorption on the catalytic performance of H3PMo12O40@C catalyst for producing 2-nitro-4-methylsulfonylbenzoic acid (NMSBA) from the oxidation of 2-nitro-4- methylsulfonyltoluene (NMST) by oxygen in acetic acid has been investigated. Six kinds of acids were added into the impregnation solution as competitive adsorbates for phosphomolybdic acid in the preparation of H3PMo12O40@C catalyst. H2SO4, HCl, HNO3, CH3COOH and H2C2O4 are beneficial to improving the catalytic activity of the H3PMo12O40@C catalyst. The corresponding optimum impregnation concentrations for H2SO4, HCl, HNO3, CH3COOH and H2C2O4 are 0.4, 0.3, 0.3, 1.0 and 0.3 mol L−1, respectively. The addition of H3PO4 exerts a negative effect on the catalytic capability of H3PMo12O40@C catalyst. The results of TEM characterization show that good dispersion of H3PMo12O40 on the surface of the H3PMo12O40@C catalyst is beneficial to ameliorating the catalytic ability of H3PMo12O40@C catalyst in the production of NMSBA from NMST by oxygen in acetic acid. The results of NH3-TPD indicate that the acidity of the H3PMo12O40@C also favors the improvement of the catalytic capability of H3PMo12O40@C in the oxidation of NMST to NMSBA.

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