scholarly journals Transhydrogenation of pentane with 1,5- and 2,4-hexadiene over CrOx/Al2O3

2020 ◽  
Author(s):  
Mustapha D. Garba ◽  
S. David Jackson
Keyword(s):  
Reaction Temperature ◽  
Thermodynamic Stability ◽  
Molecular Interaction ◽  
Kinetic Effect ◽  
Alumina Catalyst ◽  
Reaction Conditions ◽  
Unexpected Effect ◽  
Direct Hydrogenation

AbstractTranshydrogenation of pentane (P) and 1,5-hexadiene (1,5HD) and pentane and 2,4-hexadiene (2,4HD) was studied over a CrOx/alumina catalyst at 523–773 K. Thermodynamic stability differences between the conjugated (2,4-hexadiene) and non-conjugated (1,5-hexadiene) isomers indicated that transhydrogenation was favoured between pentane and 1,5-hexadiene but not pentane and 2,4-hexadiene (+ ve ∆G). At 773 K a significantly enhanced alkene yield was observed for the P/1,5HD system, clearly showing the effect of transhydrogenation. The yield of alkenes was ~ 50% and included alkylated and isomerized alkenes. Alkylation and isomerization were significant reactions under reaction conditions. Pentane was shown to affect the chemistry of 1,5HD and vice versa with the conversion of pentane significantly enhanced at all reaction temperatures, indicating a molecular interaction between the reactants even when transhydrogenation was not obvious. In contrast, no effect on the conversion of pentane was observed when the co-feed was 2,4HD. An unexpected effect of pentane on 2,4HD conversion was observed, with all reactions of cis-2,4-hexadiene (including alkylation and isomerization) being completely inhibited at low reaction temperatures (573 K and 523 K) by the presence of pentane, suggesting that pentane competes for the same sites as cis-2,4-hexadiene. Transhydrogenation activity between pentane and 1,5-hexadiene was less obvious at the lower reaction temperature, which appeared to be a kinetic effect. Direct hydrogenation of 1,5-hexadiene revealed that 1,5HD sampled the same hydrogen population for hydrogenation and transhydrogenation. Comparisons of transhydrogenation of 1-hexyne, 1,5-hexadiene, and 2,4-hexadiene with pentane have revealed significant differences in the adsorption and reaction chemistry of the three isomers.

Effects of salts on the kinetics of oxidation of alkenes by thallic salts in aqueous solutions

1981 ◽  
Vol 46 (3) ◽  
pp. 693-700 ◽  
Author(s):  
Milan Strašák ◽  
Jaroslav Majer
Keyword(s):  
Aqueous Solutions ◽  
Phase Transfer ◽  
Heterogeneous Reaction ◽  
Qualitative Model ◽  
Kinetic Effect ◽  
Tetraalkylammonium Salts ◽  
Reaction Conditions ◽  
Kinetics Of Oxidation ◽  
Kinetics Of ◽  
Heterogeneous Reaction Conditions

The kinetics of oxidation of alkenes by thallic sulphate in aqueous solutions, involving the two reaction steps-the hydroxythallation and the dethallation - was studied, and the effect of salts on the kinetics was examined; this made it possible to specify more precisely the reaction mechanism and to suggest a qualitative model of the reaction coordinate. It was found that in homogeneous as well as in heterogeneous reaction conditions, the reaction can be accelerated appreciably by adding tetraalkylammonium salts. These salts not only operate as catalysts of the phase transfer, but also exert a significant kinetic effect, which can be explained with a simplification in terms of a stabilization of the transition state of the reaction.

scholarly journals Synthesis of propylene carbonate from urea and 1,2-propylene glycol over metal carbonates

2011 ◽  
Vol 17 (3) ◽  
pp. 323-331 ◽  
Author(s):  
Jiancheng Zhou ◽  
Wu Dongfang ◽  
Birong Zhang ◽  
Yali Guo
Keyword(s):  
Reaction Time ◽  
Propylene Glycol ◽  
Propylene Carbonate ◽  
Reaction Temperature ◽  
Reaction Conditions ◽  
Lead Carbonate ◽  
Synthetic Process ◽  
Metal Carbonates ◽  
Optimal Reaction ◽  
Mixed Carbonate

A series of single-metal carbonates and Pb-Zn mixed-metal carbonates were prepared as catalysts for alcoholysis of urea with 1,2-propylene glycol (PG) for the synthesis of propylene carbonate (PC). The mixed carbonates all show much better catalytic activities than the single carbonates, arising from a strong synergistic effect between the two crystalline phases, hydrozincite and lead carbonate. The mixed carbonate with Pb/Zn=1:2 gives the highest yield of PC, followed by the mixed carbonate with Pb/Zn=1:3. Furthermore, Taguchi method was used to optimize the synthetic process for improving the yield of PC. It is shown that the reaction temperature is the most significant factor affecting the yield of PC, followed by the reaction time, and that the optimal reaction conditions are the reaction time at 5 hours, the reaction temperature at 180 oC and the catalyst amount at 1.8 wt%, resulting in the highest PC yield of 96.3%.

Synthesis of a Ruthenium Complex Based on 2,6-Bis[1-(Pyridin-2-yl)-1H-Benzo[d]Imidazol-2-yl]Pyridine and Catalytic Oxidation of (1H-Benzo[d]-Imidazol-2-yl)Methanol to 1H-Benzo[d]Imidazole-2-Carbaldehyde with H2O2

2017 ◽  
Vol 41 (2) ◽  
pp. 88-92
Author(s):  
Shenggui Liu ◽  
Rongkai Pan ◽  
Wenyi Su ◽  
Guobi Li ◽  
Chunlin Ni
Keyword(s):  
Reaction Time ◽  
Catalytic Oxidation ◽  
Reaction Temperature ◽  
Ruthenium Complex ◽  
Reaction Conditions ◽  
Molar Ratios ◽  
Optimal Reaction

2,6-Bis[1-(pyridin-2-yl)-1H-benzo[d]-imidazol-2-yl]pyridine (bpbp), which has been synthesised by intramolecular thermocyclisation of N2,N6-bis[2-(pyridin-2-ylamino)phenyl]pyridine-2,6-dicarboxamide, reacts with sodium pyridine-2,6-dicarboxylate (pydic) and RuCl3 to give [Ru(bpbp)(pydic)] which can catalyse the oxidation of (1H-benzo[d]imidazol-2-yl)methanol to 1H-benzo[d]imidazole-2-carbaldehyde by H2O2. The optimal reaction conditions were: molar ratios of catalyst to substrate to H2O2 set at 1: 1000: 3000; reaction temperature 50 °C; reaction time 5 h. The yield of (1H-benzo[d]imidazol-2-yl) methanol was 70%.

scholarly journals Selective synthesis of thioethers in the presence of a transition-metal-free solid Lewis acid

2016 ◽  
Vol 12 ◽  
pp. 2627-2635 ◽  
Author(s):  
Federica Santoro ◽  
Matteo Mariani ◽  
Federica Zaccheria ◽  
Rinaldo Psaro ◽  
Nicoletta Ravasio
Keyword(s):  
Reaction Rate ◽  
Solid Acid ◽  
Amorphous Solid ◽  
Solid Acid Catalysts ◽  
Acid Catalysts ◽  
Alumina Catalyst ◽  
Reaction Conditions ◽  
Solvent Free Conditions ◽  
Wide Range ◽  
Silica Alumina

The synthesis of thioethers starting from alcohols and thiols in the presence of amorphous solid acid catalysts is reported. A silica alumina catalyst with a very low content in alumina gave excellent results in terms of both activity and selectivity also under solvent-free conditions. The reaction rate follows the electron density of the carbinol atom in the substrate alcohol and yields up to 99% and can be obtained for a wide range of substrates under mild reaction conditions.

Synthesis of Diamine Containing Chalcone Structure by Nitroammoniation and Aldol Condensation

2019 ◽  
Vol 801 ◽  
pp. 145-150
Author(s):  
Yan Kai Huang ◽  
Qi Lin Mei ◽  
Zhi Xiong Huang ◽  
Yan Qin ◽  
Di Zhu
Keyword(s):  
Reaction Temperature ◽  
Elemental Analysis ◽  
Aldol Condensation ◽  
Raw Material ◽  
Anhydrous Ethanol ◽  
Infrared Analysis ◽  
Reaction Conditions ◽  
Optimum Reaction ◽  
Ethanol Dosage

In this paper, the structure of the photosensitive diamines was designed and the method of synthesizing such diamines was investigated. The 1-(3-aminophenyl)-3-(4-aminophenyl)-2-propen-1-one analyzed by elemental analysis and infrared analysis was synthesized through two-step experiments with Aldol condensation and Nitroammoniation process. Through the experiment the optimum reaction conditions are raw material ratio of 1:1, anhydrous ethanol dosage of 60 ml, 10 % NaOH dosage of 10 ml and reaction temperature of 25°C for 4h. The yield was about 55.4 %.

scholarly journals First-principles insight into CO hindered agglomeration of Rh and Pt single atoms on m-ZrO2

2020 ◽  
Vol 10 (17) ◽  
pp. 5847-5855
Author(s):  
Minttu M. Kauppinen ◽  
Marko M. Melander ◽  
Karoliina Honkala
Keyword(s):  
Thermodynamic Stability ◽  
First Principles ◽  
Single Atom ◽  
Reaction Conditions ◽  
Multi Scale ◽  
Single Atoms ◽  
Thermodynamic Framework ◽  
Insight Into ◽  
Non Equilibrium

Kinetic and thermodynamic stability of single-atom and nanocluster catalysts is addressed under reaction conditions within a DFT-parametrised multi-scale thermodynamic framework combining atomistic, non-equilibrium, and nanothermodynamics.

Preparation of Alkyl Polyglucoside Surfactants by One-Step

2012 ◽  
Vol 550-553 ◽  
pp. 75-79 ◽  
Author(s):  
Jia Yin Li ◽  
Yan Jun Liu ◽  
Guo Zheng ◽  
Yu Sun ◽  
Ya Ning Hao ◽  
...  
Keyword(s):  
Reaction Temperature ◽  
Reaction Conditions ◽  
Reaction Pressure ◽  
Toluenesulfonic Acid ◽  
Catalyst Type ◽  
One Step ◽  
Temperature And Pressure ◽  
Alkyl Polyglucoside

Dodecyl polyglucoside was synthesized by glucose and dodecanol using P-toluenesulfonic acid as catalyst. The effects catalyst type, proportion of material, reaction temperature and pressure were discussed in this paper. The most appropriate reaction conditions: mole ratio of laurel alcohol and glucose 6:1, mass of ratio of P-toluenesulfonic and glucose 0.008:1, reaction temperature 120°C and reaction pressure 5.0kPa.

Preparation and Characterization of Cationic Cassia Tora Gum

2013 ◽  
Vol 781-784 ◽  
pp. 526-530 ◽  
Author(s):  
Shao Ying Li ◽  
Chun Mei Niu ◽  
Hua Yu Zhong
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Water Solubility ◽  
Cold Water ◽  
Water Solution ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Cassia Tora ◽  
Dispersing Agent

Series of cationic cassia tora gum (CCTG) were synthesized using 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) as cationic etherifying agent, isopropanol-water solution as dispersing agent, in presence of sodium hydroxide under different reaction conditions. The optimum ratio for preparing the cationic cassia tora gum are that CHPTAC-CTG molar ratio is 0.6:1; NaOH-CHPTAC molar ratio is 1.3:1.The optimum conditions are that reaction temperature is 55°Cand reaction time is 3.5 h. The cold water solubility was improved apparently. The solution transmittance has corresponding relationship with the nitrogen content (N%) in the certain range, and the maximum transmittance is up to 87.2%. N% increased with the increase of reaction time and stable N% can be obtained in shorter reaction time at higher reaction temperature. The products were characterized by 13C-NMR. The heat resistance of CTG and CCTG were analyzed.

Influencing Factors of Modified PVDF Grafted onto a Blended PAMPS(PVDF-G-PAMPS) Membrane

2011 ◽  
Vol 197-198 ◽  
pp. 1267-1270
Author(s):  
Jia Xu ◽  
Gui Bao Guo ◽  
Sheng Li An
Keyword(s):  
Reaction Temperature ◽  
Proton Exchange Membrane ◽  
Vinylidene Fluoride ◽  
Ammonium Persulfate ◽  
Proton Exchange ◽  
Reaction Conditions ◽  
Membrane Conductivity ◽  
Poly Vinylidene Fluoride ◽  
Exchange Membrane ◽  
Optimal Reaction

A proton exchange membrane of blended poly (acrylamido-2- methylpropane sulfonic acid) grafted onto modified poly (vinylidene fluoride) membrane (PVDF-g-PAMPS) was prepared The influences of Na4SiO4 content, reaction temperature and time, content of ammonium persulfate and AMPS on PVDF-g-PAMPS membrane were discussed. The results show that the optimal reaction conditions are as follows: Na4SiO4 is 8%; ammonium persulfate is 0.016 mol / L; AMPS is 30 %; the reaction temperature is 80 °C and the reaction time is 1h. On the condition, PVDF-g-PAMPS membrane conductivity can reach to 1.27×10-2 S/cm.

Preparation and Properties of MgAl2O4-CaAl12O19 High Temperature Composite

2012 ◽  
Vol 512-515 ◽  
pp. 617-620
Author(s):  
Yong Hong Wang ◽  
Yan Gai Liu ◽  
Tao Yang ◽  
Zhao Hui Huang ◽  
Ming Hao Fang
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Reaction Temperature ◽  
Bending Strength ◽  
Raw Materials ◽  
Weight Ratio ◽  
Raw Material ◽  
Reaction Conditions ◽  
Optimum Reaction ◽  
Industrial Alumina

The utilization of lightweight refractories plays an important role in reducing the energy consumption of industrial furnaces. In this paper, MgAl2O4-CaA112O19 high temperature composite was synthesized via solid state reaction using magnesite, dolomite and industrial alumina as raw materials. The influences of raw materials and reaction temperature on phase compositions and microstructure of the composite were investigated by XRD and SEM，respectively. The parameters to prepare MgAl2O4-CaA112O19 high temperature composite were optimized. The results show that the optimum reaction conditions for synthesizing MgAl2O4-CaA112O19 composite is the CA6/MA weight ratio of 2:3, and the reaction temperature of 1500°C for 4h. The CaA112O19 crystals showed laminated or plate-like structure, and the MgAl2O4 showed spherical morphology. The reaction temperature had little effect on the phase compositions of MA-CA6 composite in this experiment. The content of Al2O3 in the raw material affected the phase composition of MA-CA6 composite.With the increase of the CaA112O19 amount, the bending strength of the composite decreased.

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