Chromium–aluminium orthophosphates. Part 1.—Structure, texture, surface acidity and catalytic activity in cyclohexene skeletal isomerization and cumene conversion of CrPO4–AlPO4catalysts

AlPO4 and Al2O3–AlPO4 mixed catalysts of different composition (Al/P > 1) were prepared and calcined in the temperature range 350–650°C. Such catalysts were characterized by DTA and X-ray diffraction methods, and by nitrogen adsorption studies at −196°C. Their acidity was determined using a calorimetric titration method while their catalytic activity towards the dehydration of isopropanol was determined using a pulse microcatalytic technique. The data obtained from XRD studies showed that pure AlPO4 when calcined at 650°C had a rather low crystallinity with its crystalline structure (which is of the α-cristobalite type) being characterized by poorly developed peaks. However, significant changes in the texture, surface acidity and catalytic activity were observed as a result of changing the chemical composition of the solid, with the surface area, total pore volume and surface acidity generally increasing with increasing alumina content. Sintering commenced above 550°C leading to a decrease in the surface area and to pore widening. Dehydration of isopropanol appeared to be insensitive to the structure of the catalysts investigated but was related to the surface acid density.

Download Full-text

Effect of surface acidity on the catalytic activity and deactivation of supported sulfonic acids during dehydration of methanol to DME

New Journal of Chemistry ◽

10.1039/d0nj00229a ◽

2020 ◽

Vol 44 (39) ◽

pp. 16810-16820

Author(s):

Rosanna Viscardi ◽

Vincenzo Barbarossa ◽

Daniele Mirabile Gattia ◽

Raimondo Maggi ◽

Giovanni Maestri ◽

...

Keyword(s):

Catalytic Activity ◽

Sulfonic Acid ◽

Water Resistance ◽

Surface Acidity ◽

Acid Catalyst ◽

Acid Sites ◽

Sulfonic Acids ◽

Effect Of Surface

Superiorty of the supported sulfonic acid catalyst in terms of the water resistance and efficiency of the acid sites compared to the commercial reference.

Download Full-text

Catalytic Activity of ZSM-22 Zeolites in the Skeletal Isomerization Reaction of 1-Butene

Industrial & Engineering Chemistry Research ◽

10.1021/ie960641w ◽

1997 ◽

Vol 36 (8) ◽

pp. 2990-2995 ◽

Cited By ~ 27

Author(s):

Rune Byggningsbacka ◽

Lars-Eric Lindfors ◽

Narendra Kumar

Keyword(s):

Catalytic Activity ◽

Skeletal Isomerization ◽

Isomerization Reaction

Download Full-text

Vanadium-Chromium Oxide: Effective Catalysts for Ammoxidation of 3-Picoline

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.624 ◽

2013 ◽

Vol 634-638 ◽

pp. 624-627 ◽

Cited By ~ 1

Author(s):

Feng Jiang ◽

Wei Xu ◽

Lei Niu ◽

Guo Min Xiao

Keyword(s):

Raman Spectroscopy ◽

Catalytic Activity ◽

Chromium Oxide ◽

Atmospheric Pressure ◽

High Selectivity ◽

Surface Acidity ◽

N2 Adsorption ◽

Composite Oxide ◽

Highly Active

Bulk vanadium-chromium oxide (VCrO) catalyst was prepared and characterized by N2 adsorption, XRD, NH3-TPD, H2-TPR, and Raman spectroscopy. XRD and Raman results showed that the VCrO catalyst was a kind of VV-CrIII composite oxide mainly consisted of crystalline V2O5 and CrVO4-Ⅲ (orthorhombic). NH3-TPD and H2-TPR results revealed that this catalyst had negligible surface acidity, and was easily reduced due to the formation of CrVO4-Ⅲ. Their catalytic activity was evaluated in the ammoxidation of 3-picoline to nicotinonitrile. Catalytic results showed that the bulk VCrO catalyst was highly active and selective; the nicotinonitrile selectivity and yield was up to 96.1%, 88.2% respectively at atmospheric pressure and 360 °C. The high selectivity was related closely to the low surface acidity of the catalyst.

Download Full-text