scholarly journals Vapor phase aldol condensation of methyl acetate with formaldehyde over a Ba–La/Al2O3 catalyst: the stabilizing role of La and effect of acid–base properties

RSC Advances ◽  
2017 ◽  
Vol 7 (82) ◽  
pp. 52304-52311 ◽  
Author(s):  
Qiang Bao ◽  
Wanchun Zhu ◽  
Jianbiao Yan ◽  
Chunlei Zhang ◽  
Chunli Ning ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Methyl Acetate ◽  
Aldol Condensation ◽  
Acid Base ◽  
Al2o3 Catalyst ◽  
Base Properties

Vapor phase aldol condensation of methyl acetate with formaldehyde was studied over Ba–La/Al2O3 with different amounts of lanthanum catalysts.

Vapor-phase oxidation of propylene glycol-methanol mixture to methyl lactate on CeO2/Al2O3 catalyst

2021 ◽  
pp. 92-97
Author(s):  
M.E. Sharanda ◽  
◽  
A.M. Mylin ◽  
O.Yu. Zinchenko ◽  
V.V. Brei ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
Vapor Phase ◽  
Flow Reactor ◽  
Aldol Condensation ◽  
Ethyl Lactate ◽  
Molar Ratio ◽  
Methyl Lactate ◽  
Reactor Inlet ◽  
Phase Oxidation ◽  
Al2o3 Catalyst

The vapor-phase oxidation of mixtures of propylene glycol with methanol and ethanol to methyl and ethyl lactate, respectively, on supported CeO2/Al2O3 catalyst with 10 wt.% CeO2 content was studied. The steel flow reactor with a fixed catalyst bed (4 cm3) was used. 20 wt.% solution of propylene glycol in alcohol was fed to the reactor inlet by Waters 950 pump at LHSV= 0.5-0.8 h-1. Reaction temperature and pressure were varied in the interval of 190-250 0C and 1.3-1.8 bars respectively. Compressed air was given to the reactor inlet at the molar ratio of propylene glycol/O2 = 1. The reaction products were analyzed using gas chromatography (Agilent 7820A) and 3C NMR (Bruker Avance 400) methods. Studied oxidation of propylene glycol in the presence of methanol describes by total reaction CH3CHOHCH2OH +O2 + СН3OH = CH3CHOHCOOСН3 +2H2O At first, hydroxyacetone is formed that is further oxidized to pyruvic aldehyde, which attaches alcohol to form hemiacetal. Then, hemiacetal of methyl glyoxal rearranges into methyl lactate by Cannizzaro. At 220 0C and load on a catalyst of < 2 mmol PG/gcat/h, the selectivity towards methyl lactate reaches 70 wt.% at 100 % propylene glycol conversion. The main by-products are formed as the result of acetaldehyde transformation. Acetaldehyde could be formed at hydroxyacetone aldol decondensation. In the presence of ethanol, the formation of a significant amount of acetaldehyde and its aldol condensation products as well as the formation of diethoxyethane are observed. Therefore, ethyl lactate selectivity at 100 % propylene glycol conversion does not exceed 45 %. Supported CeO2/SiO2 contact was tested in this oxidation reaction also. However, CeO2/SiO2 provides the low, up to 25%, selectivity towards methyl lactate at full propylene glycol conversion. It was shown that at the same conditions methyl lactate is formed with higher selectivity then ethyl lactate. The high methyl lactate yield up to 70 wt.% could be obtained via vapor-phase oxidation of 20% mixture of propylene glycol with methanol by air oxygen on supported CeO2/Al2O3 catalyst at 210 - 220°С and at time contact of 3-4 seconds.

The crucial role of the inter-ring hydrogen bond to explain the properties of morin

2018 ◽  
Vol 42 (10) ◽  
pp. 7691-7702 ◽  
Author(s):  
Aurélien Moncomble ◽  
Diksha Jani Thaviligadu ◽  
Anaëlle Raoumbé Djendja ◽  
Jean-Paul Cornard
Keyword(s):  
Hydrogen Bond ◽  
Crucial Role ◽  
Acid Base ◽  
Theoretical Approaches ◽  
Base Properties

The acid-base properties of morin and its complexation with the ZnII cation are investigated by experimental and theoretical approaches.

scholarly journals Conversion of D-Fructose into Ethyl Lactate Over a Supported SnO2–ZnO/Al2O3 Catalyst

2019 ◽  
Vol 3 (1) ◽  
pp. 16 ◽  
Author(s):  
Svitlana Prudius ◽  
Nataliia Hes ◽  
Volodymyr Brei
Keyword(s):  
Raw Material ◽  
Ethyl Lactate ◽  
Acid Base ◽  
Effective Catalyst ◽  
Renewable Raw Material ◽  
Al2o3 Catalyst ◽  
Base Properties

The study is directed to the search of a simple effective catalyst for ethyl lactate obtained from fructose as renewable raw material. A series of SnO2-containing oxides prepared by impregnation of alumina were characterized by several techniques in order to determine their textural and acid-base properties. The transformation of a 13% fructose solution in 98% ethanol over SnO2/Al2O3 catalysts using autoclave rotated with 60 rpm at 160 °C for 3 h was studied. It was found that doping SnO2/Al2O3 samples with ZnO improves selectivity towards ethyl lactate. The supported SnO2-ZnO/Al2O3 catalyst provides 100% fructose conversion with 55% yield of ethyl lactate at 160 °C. A possible scheme of fructose transformation into ethyl lactate on L-acid IVSn4+ sites is discussed.

Direct synthesis of dimethyl carbonate from CO2 and methanol over CaO–CeO2 catalysts: the role of acid–base properties and surface oxygen vacancies

2017 ◽  
Vol 41 (20) ◽  
pp. 12231-12240 ◽  
Author(s):  
Bin Liu ◽  
Congming Li ◽  
Guoqiang Zhang ◽  
Lifei Yan ◽  
Zhong Li
Keyword(s):  
Oxygen Vacancies ◽  
Dimethyl Carbonate ◽  
Direct Synthesis ◽  
Surface Oxygen ◽  
Acid Base ◽  
Base Properties

The addition of CaO to the CeO2 catalyst had a significant impact on the acid–base properties and amounts of oxygen vacancies on the surface catalyst.

scholarly journals Influence of acid–base properties of Mg-based catalysts on transesterification: role of magnesium silicate hydrate formation

2017 ◽  
Vol 7 (8) ◽  
pp. 1701-1712 ◽  
Author(s):  
Damien Cornu ◽  
Longfei Lin ◽  
Maya Mounir Daou ◽  
Maguy Jaber ◽  
Jean-Marc Krafft ◽  
...  
Keyword(s):  
Large Range ◽  
Hydrate Formation ◽  
Magnesium Silicate ◽  
Acid Base ◽  
Basic Properties ◽  
Base Properties

Catalysts with the strongest basic properties are not always the most efficient ones for transesterification, a series of magnesium-based materials, exhibiting a large range of acido–basic properties, was investigated.

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