Promoted TiO2 (Anatase)-Supported Vanadium Oxide Catalysts. TPR Study and Activity in Oxidation of Toluene

1996 ◽  
Vol 61 (11) ◽  
pp. 1665-1674 ◽  
Author(s):  
Marcel Antol ◽  
Katarina Prandová ◽  
Milan Hronec
Keyword(s):  
Benzoic Acid ◽  
Vanadium Oxide ◽  
High Selectivity ◽  
Negative Influence ◽  
Molar Ratio ◽  
Toluene Oxidation ◽  
Tio2 Anatase ◽  
Temperature Programmed ◽  
Positive Effect ◽  
Very High

Vanadium oxide doped with K, Li, Bi, Sb, Te, U or Mo oxide, supported on TiO2 - anatase, was studied by temperature programmed reduction (TPR). The influence of the addition of promoters (up to molar ratio M : V = 0.5) to 5 wt.% V2O5/TiO2 catalyst on the TPR profile is presented in correlation with their catalytic activity in the vapor phase oxidation of toluene. All promoters, except Bi2O3, decrease the catalyst reducibility and decrease the rate of the toluene oxidation. A strong negative influence on the activity of the toluene oxidation have K, Li, and Te oxides. However, the presence of all tested promoters in the molar ratio M : V = 0.05 has a positive effect on the selectivity of benzoic acid formation. A further increase of this ratio leads to a decrease of the selectivity in the case of U, Mo and mainly K oxides, while with Li, Bi, Sb, and Te oxides, the selectivity remains almost unchanged. No correlation between TPR profiles of doped catalysts and their selectivity was found. The most effective promoter of vanadia catalysts for the benzoic acid production is Sb oxide, possessing a very high selectivity at high conversion of toluene.

Oxidation of Toluene Over V2O5-Sb2O3/TiO2 Catalysts. Enhancement of Selectivity Towards Benzoic Acid

1996 ◽  
Vol 61 (11) ◽  
pp. 1675-1680 ◽  
Author(s):  
Marcel Antol ◽  
Alexander Kaszonyi ◽  
Milan Hronec
Keyword(s):  
Carbon Dioxide ◽  
Benzoic Acid ◽  
Oxidation Products ◽  
Temperature Programmed Reduction ◽  
Reaction Parameters ◽  
Toluene Oxidation ◽  
Methyl Group ◽  
Temperature Programmed ◽  
Positive Effect ◽  
Methyl Group Oxidation

The effect of reaction parameters, additives and cooxidants on the selectivity of toluene oxidation to benzoic acid in the vapor phase has been studied. The presence of ethanol as cooxidant in the reaction stream does not improve the selectivity of toluene oxidation towards partial oxidation products via methyl group oxidation. However, the presence of carbon dioxide has a positive effect on the selectivity to benzoic acid formation. The catalysts were characterized by temperature programmed reduction.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

scholarly journals Nanosheet-Like Ho2O3 and Sr-Ho2O3 Catalysts for Oxidative Coupling of Methane

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 388
Author(s):  
Yuqiao Fan ◽  
Changxi Miao ◽  
Yinghong Yue ◽  
Weiming Hua ◽  
Zi Gao
Keyword(s):  
Oxidative Coupling ◽  
Temperature Programmed Desorption ◽  
Oxidative Coupling Of Methane ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Oxygen Species ◽  
N2 Adsorption ◽  
Basic Sites ◽  
Chemisorbed Oxygen ◽  
Temperature Programmed

In this work, Ho2O3 nanosheets were synthesized by a hydrothermal method. A series of Sr-modified Ho2O3 nanosheets (Sr-Ho2O3-NS) with a Sr/Ho molar ratio between 0.02 and 0.06 were prepared via an impregnation method. These catalysts were characterized by several techniques such as XRD, N2 adsorption, SEM, TEM, XPS, O2-TPD (temperature-programmed desorption), and CO2-TPD, and they were studied with respect to their performances in the oxidative coupling of methane (OCM). In contrast to Ho2O3 nanoparticles, Ho2O3 nanosheets display greater CH4 conversion and C2-C3 selectivity, which could be related to the preferentially exposed (222) facet on the surface of the latter catalyst. The incorporation of small amounts of Sr into Ho2O3 nanosheets leads to a higher ratio of (O− + O2−)/O2− as well as an enhanced amount of chemisorbed oxygen species and moderate basic sites, which in turn improves the OCM performance. The optimal catalytic behavior is achievable on the 0.04Sr-Ho2O3-NS catalyst with a Sr/Ho molar ratio of 0.04, which gives a 24.0% conversion of CH4 with 56.7% selectivity to C2-C3 at 650 °C. The C2-C3 yield is well correlated with the amount of moderate basic sites present on the catalysts.

scholarly journals Selective Catalytic Oxidation of Toluene to Benzaldehyde: Effect of Aging Time and Calcination Temperature Using CuxZnyO Mixed Metal Oxide Nanoparticles

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 354
Author(s):  
Khadijah H. Alharbi ◽  
Ali Alsalme ◽  
Ahmed Bader A. Aloumi ◽  
Mohammed Rafiq H. Siddiqui
Keyword(s):  
Metal Oxide ◽  
Calcination Temperature ◽  
Aging Time ◽  
Metal Oxide Nanoparticles ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
Mixed Metal Oxide ◽  
Toluene Oxidation ◽  
Mixed Metal ◽  
Selective Catalytic Oxidation

Oxidation is an important organic transformation, and several catalysts have been reported for this conversion. In this study, we report the synthesis of mixed metal oxide CuxZnyO, which is prepared by a coprecipitation method by varying the molar ratio of Cu and Zn in the catalytic system. The prepared mixed metal oxide CuxZnyO was evaluated for catalytic performance for toluene oxidation. Various parameters of the catalytic evaluation were studied in order to ascertain the optimum condition for the best catalytic performance. The results indicate that aging time, calcination temperature, reaction temperature, and feed rate influence catalytic performance. It was found that the catalyst interfaces apparently enhanced catalytic activity for toluene oxidation. The XRD diffractograms reveal the crystalline nature of the mixed metal oxide formed and also confirm the coexistence of hexagonal and monoclinic crystalline phases. The catalyst prepared by aging for 4 h and calcined at 450 °C was found to be the best for the conversion of toluene to benzaldehyde while the reactor temperature was maintained at 250 °C with toluene fed into the reactor at 0.01 mL/min. The catalyst was active for about 13 h.

Preparation of Silica-Supported Nickel Molybdenum Phosphides by Temperature-Programmed Reduction Technique

2007 ◽  
Vol 124-126 ◽  
pp. 1765-1768 ◽  
Author(s):  
So Yeon Lee ◽  
Yong Kul Lee ◽  
S.Ted Oyama ◽  
Seok Hee Lee ◽  
Hee Chul Woo
Keyword(s):  
Single Phase ◽  
Reduction Rate ◽  
Reduction Reaction ◽  
Molar Ratio ◽  
Infrared Spectrometry ◽  
Molybdenum Oxides ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
Ammonium Hydrogen ◽  
Temperature Programmed

Silica supported nickel molybdenum phosphides (NiMoP/SiO2) were successfully prepared by temperature-programmed reduction (TPR) reaction of phosphorous-impregnated nickel molybdenum oxides (NiMoO4) precursors with hydrogen at relatively low temperatures (530 – 590 oC) and characterized by Fourier transform-Infrared spectrometry (FT-IR), X-ray diffraction (XRD), Electron probe microanalysis (EPMA) and Temperature-programmed reduction reaction (TPR). The process of solid transformation and properties of materials prepared from ammonium hydrogen phosphate (AMP)-impregnated samples were compared with those of phosphide made from phosphoric acid (PAC)-impregnated samples. Results show that the formation of a single NiMoP phase on silica significantly depends on reduction rates, phosphorous sources and phosphorous loadings. A single phase of NiMoP on SiO2 was particularly promoted at a below 5 oC/min of reduction rate and the starting molar ratio of Ni/Mo/P=1/1/1. A single phase of crystalline NiMoP on silica was produced from AMP-impregnated samples, while other phases of MoP, Ni2P, or NiMoP2 were appeared from PAC-impregnated samples with loading. The new phase of NiMoP2 was occurred with increasing phosphorous loading (above Ni/Mo/P=1/1/2.5) as a result of facilitated contact on the surface between the Ni-Mo bimetallic component and the phosphorous reagent

Can Corporate Social Responsibility Decrease the Negative Influence of Financial Distress on Accounting Quality?

2021 ◽  
Vol 13 (19) ◽  
pp. 11124
Author(s):  
Jun Hyeok Choi ◽  
Saerona Kim ◽  
Dong-Hoon Yang ◽  
Kwanghee Cho
Keyword(s):  
Corporate Social Responsibility ◽  
Social Responsibility ◽  
Earnings Management ◽  
Financial Distress ◽  
Negative Influence ◽  
Accounting Quality ◽  
Distressed Firms ◽  
Corporate Social ◽  
The Impact ◽  
Positive Effect

This study aimed to test how corporate social responsibility (CSR) can affect the impact of corporate financial distress on earnings management. Based on the existing literature, distressed firms tend to hide their financial crises through earnings manipulation. However, as CSR can positively affect companies in terms of performance, risk reduction, and market response, the better a firm’s CSR is the less managers will attempt earnings management even if they experience temporary distress. Consistent with the literature, test results using Korean-listed companies show that distress increased earnings management, and we confirmed that CSR weakened the positive effect of distress on earnings management. After testing each of the CSR subcategories, significant results were found mainly on environmental performance, reflecting the globally increasing interest in environmental issues. This study contributes to the literature on distress and earnings management, which rarely considers CSR as a moderating factor.

The effect of seed rate and nitrogen fertilizer on the yield and nutritive value of oat-vetch mixtures

1989 ◽  
Vol 112 (1) ◽  
pp. 57-66 ◽  
Author(s):  
N. Moreira
Keyword(s):  
Nitrogen Fertilizer ◽  
Crude Protein ◽  
Nutritive Value ◽  
High Yield ◽  
Mineral Nutrient ◽  
Yield Response ◽  
N Nutrition ◽  
North East ◽  
Positive Effect ◽  
Very High

SummaryExperiments were conducted on the seed rates of the components of oat-vetch mixtures combined with varying rates of nitrogen fertilizer in a rainfed area of north-east Portugal in 1982–3 and 1984–5.Forage oats grown alone showed a very high yield response to N and rainfall ranging from 30 to 18·2 t D.M./ha, but had a very low crude protein concentration (37–54 g/kg D.M.) and a poor mineral nutrient composition.The increased use of vetch in the seed mixture had a buffering effect on dry-matter (D.M.) yield but this depended very much on crop N nutrition. For N-deficient conditions vetch inclusion increased the D.M. yield and had a strong positive effect on total forage crude protein (CP) and mineral composition. When crop N nutrition was good, very high D.M. yields (> 12 t D.M./ha) were possible using a high proportion of oats, with vetch making a reduced contribution to the yield and nutritive value of total forage.Seed rates suggested in the literature for Mediterranean conditions are adequate for low N inputs and low available soil N, but not for high D.M. yields which can only be obtained by using a higher proportion of oats and adequate N fertilizer.

scholarly journals MONETARY POLICY AND TELECOMMUNICATION OUTPUT IN NIGERIA

2020 ◽  
Vol 3 (2) ◽  
pp. 62-73
Author(s):  
John Abiodun Akinde ◽  
Elijah Oludayo
Keyword(s):  
Monetary Policy ◽  
Money Supply ◽  
Negative Relationship ◽  
Negative Influence ◽  
Favourable Effect ◽  
Data Series ◽  
Long Run ◽  
Integration Test ◽  
Short Run ◽  
Positive Effect

Different policies impact on the growth of the telecommunication sector in Nigeria. One of these policies which influence the expansion or contraction of the telecommunication output is monetary policy. To this end, this research examined the effect of monetary policy on telecommunication output in Nigeria. For the purpose of analysis, time series secondary data were sourced from Central Bank of Nigeria (CBN) statistical bulletin covering the periods1986 to 2018. Autoregressive Distributed Lag (ARDL) technique was employed after examining the stationarity of the data series using Augmented Dickey-Fuller technique. The bound co-integration test revealed that there is long run equilibrium between the monetary policy variables employed and telecommunication output. The ARDL result revealed that money supply had significant and positive effect on telecommunication output in the short and long run; liquidity ratio produced an insignificant and negative relationship with telecommunication output in the short run and insignificant positive effect in the long run; exchange rate had insignificant negative effect in the short run and a significant positive effect on telecommunication output in the long run; consumer price index had significant negative influence on telecommunication outputboth in the short run and long run. The study concluded that monetary policy stimulates telecommunication output in Nigeria. Thus, it was recommended that the monetary authority should pursue an expansionary monetary policy to sustain the positive influence of money supply on telecommunication output in Nigeria while rolling out policy to reduce the liquidity ratio of banks in the short run but increase it in the long run so that the long term favourable effect of liquidity ratio can be felt on telecommunication output.  

scholarly journals Teachers’ ratings of the informativeness and usefulness of cognitive assessment reports: Does dynamic assessment make a difference?

2014 ◽  
Vol 46 (1) ◽  
pp. 118-144
Author(s):  
Ivana Vulic ◽  
Ana Altaras-Dimitrijevic ◽  
Zorana Jolic-Marjanovic
Keyword(s):  
School Readiness ◽  
School Psychologists ◽  
Cognitive Assessment ◽  
Dynamic Assessment ◽  
Empirical Support ◽  
Cognitive Problem ◽  
Positive Effect ◽  
Preliminary Phase ◽  
Very High ◽  
Assessment Reports

Dynamic assessment is presumed to reveal specific difficulties in cognitive problem solving and determine the kinds of support which may aid in overcoming them. In the present study we examined whether these additional data provided by dynamic assessment contribute to the informativeness and usefulness of assessment reports, as rated by teachers. In the preliminary phase, nine preschoolers were tested with the adapted Serbian WISC, containing an additional block of dynamic assessment. In the main phase, two groups of elementary teachers (Nstat= 41, Ndyn= 44) rated the informativeness, usefulness, and clarity of reports based on either static, or static+dynamic assessment of three children from the preliminary sample. The results indicate a significant positive effect of dynamic assessment on teachers? ratings of the informativeness of reports (particularly regarding the child?s reactions to adult scuffolding) and their combined ratings of several aspects of the reports? usefulness. The reports did not differ with respect to clarity, and their informativeness and usefulness were generally rated very high. The findings thus provide empirical support for the proposed advantages of dynamic assessment, encourage its use in assessing school readiness, and urge school psychologists to regularly inform teachers on their observations from both static and dynamic cognitive assessment.

scholarly journals Simultaneous Catalytic Oxidation of a Lean Mixture of CO-CH4 over Spinel Type Cobalt Based Oxides

2020 ◽  
Vol 15 (2) ◽  
pp. 490-500
Author(s):  
Neha Neha ◽  
Ram Prasad ◽  
Satya Vir Singh
Keyword(s):  
Mixed Oxides ◽  
Structural Disorder ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
Total Oxidation ◽  
Spinel Type ◽  
Molar Ratios ◽  
Long Term Stability ◽  
Nickel Cobalt ◽  
Temperature Programmed

A series of nickel-cobalt bimetal oxides in varying molar ratios and its single metal oxides were synthesized by reactive calcination of coprecipitated basic-carbonates. Several characterization techniques, such as: Bruneuer Emmett Teller (BET), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR), and Hydrogen Temperature Programmed Reduction (H2-TPR), were performed over the oxides. Activities of oxides were evaluated in methane total oxidation in the presence or the absence of CO. The best catalytic performance was observed over NiCo catalyst with a Ni/Co molar ratio of 1:1, and the complete conversion of CO-CH4 mixture was achieved at 390 °C. Moreover, the presence of carbon monoxide improves CH4 total oxidation over nickel-cobalt mixed oxides. Structural analysis reveals that the insertion of nickel into the spinel lattice of cobalt oxide causes the structural disorder, which probably caused the increase of the amount of octahedrally coordinated divalent nickel cations that are responsible for catalytic activity. Stability of the best-performed catalyst has been tested in the two conditions, showing remarkable long-term stability and thermal stability, however, showed deactivation after thermally ageing at 700 °C. Copyright © 2020 BCREC Group. All rights reserved 

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