Mahendra Somabhai Patel

C02 and NO chemisorptions on Moγ-Al2O3 catalysts

Abstract CO 2 and NO chemisorptions, FT-IR, and TGA techniques were used to study the surface structure of calcined and reduced Mo γ- Al 2 O 3 catalysts. The results clearly show that there are three distinct surface structures whose presence is dependent on the molybdenum loading. At low loadings, molybdenum interacts strongly with the alumina surface hydroxyl groups to form “strong Mo interaction species.” The molybdenum is highly dispersed, difficult to reduce, and has a low coordination number (C.N.). At medium loadings before the monolayer coverage, the MoOMo interaction increases and the Mo-support interaction may decrease to form “Mo interaction species.” Such formed molybdenum is well dispersed, reducible, and has a high C.N. The CO 2 uptake at the monolayer coverage is almost zero. Above the monolayer coverage, excess molybdenum aggregates to form bulk MoO 3 and Al 2 (MoO 4 ) 3 species at the expense of a small amount of well-dispersed molybdenum species to create some exposed alumina surface. The molybdenum formed under this condition is easily reduced, has a large particle size, and has a high C.N. The bulk MoO 3 species interacts with the support to form Al 2 (MoO 4 ) 3 at high calcination temperatures (⩾600 °C). All the molybdenum phases rearrange and agglomerate to create some free alumina and to decrease the molybdenum dispersion after H 2 reduction. The extent of rearrangement and agglomeration depends on the degree of reduction. At low loadings, only a small fraction of free alumina is recovered because of the low reducibility. A significant amount of free alumina is recovered at medium and high loadings due to the high reducibility.

Development of A Micro Hydroprocessing Test for Rapid Evaluation of Catalysts

Abstract The currently available rapid microactivity (MAT) tests based on the hydrodesulfurization (HDS) of thiophene or benzothiophene at atmospheric or elevated pressures for ranking the hydroprocessing/hydrotreating catalysts are applicable only to catalysts belonging to the same compositional family and also are limited to determining only their HDS activities. We present here a simple and rapid Micro Hydroprocessing Test (MHT) procedure developed in our laboratory to measure and rank hydroprocessing catalysts for their HDS, hydrodenitrogenation (HDN), and hydrogenation (HYD) activities simultaneously. The catalyst ranking obtained from using this MHT procedure matches that obtained from catalytic evaluations using real petroleum feedstocks. In addition, this MHT procedure makes it possible to rank catalysts belonging to different compositional families.

CO2 and NO chemisorptions on Mo/γ-Al2O3 catalysts

Etude par spectrometrie infrarouge et par thermogravimetrie de la structure de la surface du catalyseur Mo/Al 2 O 3