Vapor Phase Catalytic Transformations of Terpene Hydrocarbons in the C10H16 Series. II. Aromatization of α-Pinene over Chromia–Alumina

1972 ◽  
Vol 50 (1) ◽  
pp. 113-118 ◽  
Author(s):  
A. Stanislaus ◽  
L. M. Yeddanapalli
Keyword(s):  
Vapor Phase ◽  
Alumina Support ◽  
Pure Alumina ◽  
Catalytic Transformations ◽  
Alumina Catalysts

The aromatization of α-pinene in the vapor phase over chromia gel and chromia–alumina catalysts prepared from aluminas of different acidity has been studied. The acidity of alumina support has a remarkable influence on the composition of the aromatics resulting from the dehydrogenation of α-pinene. Over weakly acidic chromia–alumina doped with 1% sodium catalyst, α-pinene is aromatized to p-cymene, 1,2,4- and 1,2,3-trimethylbenzenes with traces of toluene and xylenes, whereas over the strongly acidic chromia – pure alumina and chromia–alumina containing 5% HF catalysts it gives considerable amount of m-cymene, toluene, and tetramethylbenzenes. A satisfactory mechanism to explain the formation of these compounds is offered.

Vapour phase catalytic transformations of terpene hydrocarbons in the C10H16 series. III. Dehydrogenation of Δ3-carene over modified chromia and chromia–alumina catalysts

1976 ◽  
Vol 54 (21) ◽  
pp. 3458-3463 ◽  
Author(s):  
V. Krishnasamy ◽  
L. M. Yeddanapalli
Keyword(s):  
Hydrofluoric Acid ◽  
Vapour Phase ◽  
Potassium Ions ◽  
Total Conversion ◽  
Fluoride Ions ◽  
Catalytic Transformations ◽  
Alumina Catalysts

The vapour phase dehydrogenation of 3-carene has been studied over chromia, chromia–alumina, chromia doped with potassium, and chromia–alumina doped with potassium and fluoride ions. Addition of potassium to chromia and chromia–alumina up to 1% by weight does not significantly affect the overall conversion of 3-carene whereas it increases its dehydrogenation to p- and m-cymenes. Potassium ions above 1% lower both the total conversion and dehydrogenation of 3-carene to cymenes. The ratio of p- to m-cymene over chromia–alumina is enhanced by added potassium ions up to 2%, but over chromia it remains unaffected. Addition of potassium to chromia decreases the formation of menthanes and menthadienes but its addition to chromia–alumina reduces the formation of menthanes and increases that of menthadienes. Impregnation of chromia–alumina with hydrofluoric acid suppresses the formation of menthadienes and increases that of menthanes. All these are explained in terms of the effect of added potassium and fluoride ions on the acidity of the catalysts.

scholarly journals The Effect of the Method of Preparation on the Textural, Acidic and Catalytic Properties of Chromia–Alumina Catalysts

1996 ◽  
Vol 13 (5) ◽  
pp. 355-365
Author(s):  
Th. El-Nabarawy ◽  
L.B. Khalil ◽  
A. M. Youssef
Keyword(s):  
Water Vapour ◽  
Catalytic Properties ◽  
Acid Sites ◽  
Adsorption Properties ◽  
Pure Alumina ◽  
First Order ◽  
First Order Kinetics ◽  
Structure Sensitive ◽  
Adsorption Of Nitrogen ◽  
Alumina Catalysts

Pure alumina 'A' and chromia–alumina catalysts containing 25 mol% Cr2O3 (IAC, IIAC and IIIAC) were prepared by impregnation, coprecipitation and coating techniques, respectively. The adsorption of nitrogen at 77 K and of benzene and water vapour at 308 K was determined. The chemisorption of pyridine at 400 K was measured and the surface acidities calculated. The conversion of 2-propanol and cracking of cumene were investigated using the pulse microcatalytic technique. Coating alumina with chromia causes considerable changes in the textural and adsorption properties, impregnation of alumina with chromia leads to smaller variations while coprecipitation gives intermediate changes in textural and adsorption properties. The same was found true for the surface acidities as determined by the chemisorption of pyridine. The dehydration of 2-propanol and cracking of cumene follow first-order kinetics. The dehydration of propanol on alumina and chromia–alumina catalysts is a structure-insensitive reaction independent of the surface area but related to the surface acid density. The cracking of cumene is a structure-sensitive reaction depending on both the extent of the surface and the number of acid sites.

scholarly journals Vapour phase catalytic transformations of terpene hydrocarbons in the C10H16 series. IV. Effect of nitrogen, hydrogen, and pyridine on the dehydrogenation of Δ3-carene over chromia and chromia-alumina catalysts

1977 ◽  
Vol 55 (16) ◽  
pp. 3046-3049 ◽  
Author(s):  
V. Krishnasamy ◽  
L. M. Yeddanapalli
Keyword(s):  
Partial Pressure ◽  
Vapour Phase ◽  
Catalytic Transformations ◽  
Partial Pressures ◽  
Alumina Catalysts ◽  
Catalyst Surfaces

The influences of nitrogen, hydrogen, and pyridine on the conversion of 3-carene into various products over chromia catalyst at 450 °C and over chromia–alumina at 400 °C have been investigated. Nitrogen acts as a diluent over these catalysts; hydrogen at low partial pressures enhances the formation of cymenes over chromia, but suppresses its formation over chromia–alumina. Increase of the partial pressure of hydrogen increases the proportion of men thanes over chromia–alumina, but decreases it over chromia catalyst. Pyridine suppresses the over-all conversion of 3-carene and the formation of cymenes over chromia and chromia–alumina; however, it increases the formation of menthadienes over chromia–alumina. These observations are explained in terms of the acidity of chromia and chromia–alumina, the diluting effects of nitrogen, hydrogen, and pyridine, and their ability to adsorb and desorb over the catalyst surfaces.

Hydrogen production via surrogate biomass gasification using 5% Ni and low loading of lanthanum co-impregnated on fluidizable γ-alumina catalysts

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Adriana Sánchez Enríquez ◽  
Daniel G. González Castañeda ◽  
Alan R. Calzada Hernández ◽  
Ivan Cruz Reyes ◽  
Benito Serrano Rosales
Keyword(s):  
Hydrogen Production ◽  
Reaction Time Data ◽  
Favorable Effect ◽  
Time Data ◽  
Alumina Support ◽  
Recent Contribution ◽  
Catalytic Gasification ◽  
Crystallite Sizes ◽  
Analysis Package ◽  
Alumina Catalysts

AbstractNickel on alumina support offers opportunity for gasification of biomass for hydrogen production. In a recent contribution from our research team, (González Castañeda, D. G., et al. 2019) showed that cerium or lanthanum co-impregnation at 2 wt% with nickel may have a favorable effect for biomass catalytic gasification. However, and given an observed influence of lanthanum on the formation of small Ni crystallite sizes, five Ni/γ-Al2O3 based fluidizable La promoted catalysts were studied. Nickel-alumina catalysts promotion was effected varying La in the 0.5 and 1.0 wt% range. Once impregnation precursors loaded, they were reduced at 480 °C via an activation step. Catalysts were characterized using BET, XRD, AA, TPR, TPD, H2-chemisorption, TEM-EDX and FTIR. Catalyst performance was established in a fluidized CREC Riser Simulator, using: a) glucose as surrogate biomass, b) 600 °C, c) steam/biomass (S/B) ratio of 1, d) catalyst /biomass (C/B) ratio of 3.2 and e) 20 s reaction time. Data obtained was analyzed using an ANOVA statistical data analysis package with the 5 wt% Ni and 0.5–1 wt% La and Ce on γ-Al2O3 catalysts, prepared using a pH of 1 of impregnating solution were the best yielding 0.53–0.56 hydrogen molar fractions. These catalysts also gave a 39% reduced coke, and this while compared with the coke formed on the 2% Ce – 5 wt%Ni/γ-Al2O3 (González Castañeda, D. G., et al. 2019). This promising performance was assigned to the dominant NH3-TPD medium acidity, the high catalyst specific surface (∼140 m2/g), and the good 9% metal dispersion with 9–10 nm nickel crystallites.

The role of alumina support in the deoxygenation of rapeseed oil over NiMo–alumina catalysts

2011 ◽  
Vol 176 (1) ◽  
pp. 409-412 ◽  
Author(s):  
Peter Priecel ◽  
Libor Čapek ◽  
David Kubička ◽  
František Homola ◽  
Petr Ryšánek ◽  
...  
Keyword(s):  
Rapeseed Oil ◽  
Alumina Support ◽  
Alumina Catalysts

Crystallization of ferrierite (FER) on a porous alumina support by a vapor-phase transport method

1999 ◽  
Vol 32 (1-2) ◽  
pp. 159-168 ◽  
Author(s):  
Takaaki Matsufuji ◽  
Norikazu Nishiyama ◽  
Korekazu Ueyama ◽  
Masahiko Matsukata
Keyword(s):  
Vapor Phase ◽  
Porous Alumina ◽  
Alumina Support ◽  
Vapor Phase Transport ◽  
Vapor Phase Transport Method ◽  
Phase Transport ◽  
Transport Method

Protection of rhodium/alumina catalysts by potassium functionalization of the alumina support

1991 ◽  
Vol 95 (10) ◽  
pp. 4028-4033 ◽  
Author(s):  
Mohamed I. Zaki ◽  
Todd H. Ballinger ◽  
John T. Yates
Keyword(s):  
Alumina Support ◽  
Alumina Catalysts

Vapor Phase Catalytic Transformations of Terpene Hydrocarbons in the C10H16 Series. I. Isomerization of α-Pinene over Alumina

1972 ◽  
Vol 50 (1) ◽  
pp. 61-74 ◽  
Author(s):  
A. Stanislaus ◽  
L. M. Yeddanapalli
Keyword(s):  
Vapor Phase ◽  
Strong Acid ◽  
Acid Sites ◽  
Acid Strength ◽  
Selectivity Ratio ◽  
Reaction Products ◽  
Primary Products ◽  
Tricyclic Compounds ◽  
Strong Acid Sites ◽  
Alumina Catalysts

The isomerization of α-pinene in the vapor phase over alumina catalysts of varying acid strength has been studied. The isomerization proceeds via two parallel paths, one giving bi- and tricyclic products such as camphene, β-pinene, tricyclene, and bornylene and the other giving rise to monocyclic compounds such as dipentene, terpinolene, α-terpinene, γ-terpinene, p-cymene, and p-menthene. Dependence of the distribution of reaction products on space time reveals that camphene, β-pinene, tricyclene, dipentene, and terpinolene are the primary products. The acid strength of alumina catalysts has a remarkable influence on the selectivity ratio of bi- and tricyclic to monocyclic products, the strong acid sites favoring the formation of monocyclic products. From the study of the reactions of camphene and tricyclene over the same catalysts under similar conditions it has been concluded that the decrease in the selectivity ratio with increasing acid strength of the catalysts is mainly due to the further isomerization of the bi- and tricyclic compounds to monocyclic products which takes place only on the strong acid sites.

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