Showing papers by "Mohan S. Rana published in 2007"
TL;DR: In this paper, different technologies for residua processing: thermal, catalytic fixed and ebullated types of hydroconversion are reviewed and discussed, and a possibility of combining the advantages of these technologies together with suitable catalyst with enhanced and controlled cracking activity is also analyzed.
883 citations
TL;DR: In this article, the support effect was analyzed for hydrodesulfurization CoMo catalysts prepared with EDTA as the chelating agent, and it was found that the changes in HDS activity with the type of support are related to different levels of promotion of Mo by Co, and to changes in sulfidation patterns induced by different interactions of the active phase precursors with each support.
101 citations
TL;DR: In this article, it has been widely recognized that, for deep removal of these contaminants by hydroprocessing, research must be more oriented to the catalyst developments, rather than the process conditions.
Abstract: The environmental regulation pressure is being increased to reduce precursors of pollution contaminants (sulfur, nitrogen, and aromatics) in fuels to lower levels. There are various processes to upgrade heavy and extra-heavy crude oils, such as solvent deasphalting, thermal conversion, catalytic conversion, distillation, and hydroprocessing. Hydroprocessing not only upgrades the crude oil but also produces synthetic crude oil that has a lower impurities content and a higher liquid yield of products. The fuels upgrading currently is achieved in refinery hydroprocessing units using different new-generation catalysts, along with several modifications of process conditions such as multistage reactors, type of catalyst loading, and reactor internals. However, it has been widely recognized that, for deep removal of these contaminants by hydroprocessing, research must be more oriented to the catalyst developments, rather than the process conditions. Actual commercial catalysts are based on well-known and studied...
90 citations
TL;DR: In this article, a co-impregnation method and sequential impregnation of catalysts was used to improve the performance of dibenzothiophene (DBT) in HDS at 3.3 MPa and 340°C.
50 citations
TL;DR: In this article, the influence of H2S (0.5596 kPa) on Maya crude hydrotreating is investigated in an integral fixed bed up-flow micro reactor.
36 citations
TL;DR: In this paper, a systematic study for a concept governing support effect in heavy oil hydrotreating (HDT) catalysts is performed, which confirms that coke and metals deposition on the surface of catalyst is most probably near the pore mouth.
Abstract: A systematic study for a concept governing support effect in heavy oil hydrotreating (HDT) catalysts is performed. Different Al2O3 and its mixed oxides supports were prepared and CoMo supported catalysts were tested for Maya heavy crude oil hydrotreating. Fresh and spent catalysts are characterized with N2 adsorption-desorption, element analysis, and scanning electron microscopy-energy dispersion analysis by x-ray (SEM-EDAX), which confirms that coke and metals deposition on the surface of catalyst is most probably near the pore mouth. It is also demonstrated from these results that asphaltene conversion depends on the pore diameter of the catalyst, while other hydrotreating conversions (hydrodesulfurization (HDS), hydrodenitogenation (HDN), and in some extent hydrodemetallization (HDM)) are more likely affected by the nature of active metal distribution. The evaluation of alumina mixed oxide (TiO2, ZrO2, B2O3, and MgO) supported catalysts indicates that supports with basic nature have better sta...
33 citations
TL;DR: In this article, a reference NiMo supported on gamma alumina having wide pore diameter is used to evaluate hydrodemetallation (HDM) and hydrodesulfurization (HDS) activities.
Abstract: The deactivation of a hydrotreating catalyst is investigated in a batch reactor by using Maya heavy crude as a feed. A reference catalyst NiMo supported on gamma alumina having wide pore diameter is used to evaluate hydrodemetallation (HDM) and hydrodesulfurization (HDS) activities. It is found that, with increasing contact time, the conversion and deposits increase. The pore size distribution results show that surface area and total pore volume significantly reduce on the spent catalysts due to coke deposits. However, loss of these properties is reversed upon regeneration of the spent catalysts. It is observed from SEM study that coke preferably deposits on the pore mouth whereas vanadium is more evenly distributed throughout the catalyst particles. These deposits cause the deactivation of HDM activity; however, the reason for the loss of HDS activity is only the presence of metal deposits which may cover active sites.
31 citations
TL;DR: In this article, the effect of asphaltene contained in heavy crude on the deactivation of NiMo catalysts was studied. But the authors focused on the degradation of the catalysts.
Abstract: The effect of asphaltene contained in Maya heavy crude on the deactivation is studied. Different heavy feeds are prepared by the mixing of Maya with desulfurized diesel. A standard NiMo catalyst is used in a batch reactor to evaluate hydrodemetallation (HDM), hydrodesulphurization (HDS), and asphaltene (HDAsp) conversion. Textural properties of the spent catalysts are studied by pore size distribution and x-ray diffraction (XRD). Metals and coke deposition on the deactivated catalysts are also measured. It is found that HDM and HDAsp activities decrease with increasing concentration of asphaltene in feed, whereas the opposite trend is observed in the case of HDS. Both deposits of coke and vanadium on the catalyst's surface increase with the concentration of asphaltene in feed. The presence of asphaltene is the main reason to decrease surface area and total pore volume and hence it causes deactivation.
26 citations
TL;DR: In this paper, the effect of adding Ti and P to NiMo/ab Al2O3 catalysts in heavy Maya crude was investigated and the results showed that not all the catalyst functionalities respond equally well to the addition of Ti and p to the catalyst formulation.
Abstract: The effect of adding Ti (4.5 wt%) and P (∼1.0 wt%) by several routes to a NiMo/ab Al2O3 catalyst on the hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodemetallization (HDM), and hydrodeasphaltenization (HDAs) of heavy Maya crude was investigated. The results show that not all the catalyst functionalities respond equally well to the addition of Ti and P to the catalyst formulation. There is not a single catalyst formulation that can achieve optimum performance in all the catalyst functionalities. For HDS, Ti incorporation increases activity but the route by which P is added afterwards can improve or be detrimental to HDS activity. For HDN, the incorporation of P to the catalyst can lead to significant improvements in catalytic activity and catalyst stability. Ti increases HDM activity but the addition of P to the catalyst is detrimental to this functionality. For the elimination of asphaltenes, the catalyst supported on pure alumina is the best. So for HDAs, no benefit is obtained by...
17 citations
TL;DR: In this article, different pore diameter alumina CoMo-supported catalysts were prepared and their catalytic effect was estimated and the fresh and spent catalysts characterized by textural properties; and the average poreiameter of a fresh catalyst was found to be proportional to the HDM and HDA conversions.
Abstract: Studies of hydrodeasphaltenization (HDAs) and hydrodemetallization (HDM) of Maya heavy crude oil at temperature of 380°C and pressure of 5.4 MPa have been carried out in a high pressure microreactor. Different pore diameter alumina CoMo-supported catalysts were prepared and their catalytic effect is estimated. The fresh and spent catalysts were characterized by textural properties; and the average pore diameter of a fresh catalyst was found to be proportional to the HDM and HDA conversions. The hydrogen elemental analysis of reactant and products indicated that asphaltene conversion is a combination of cracking and hydrogenation (HYD), since HDM correlated well with HDAs, which is due to the complex nature of both molecules (asphaltene and metals).
TL;DR: In this article, the authors evaluated the performance of CoMo and NiMo catalysts for thiophene and SRGO hydrodesulfurization (HDS) in an atmospheric pressure and batch reactor respectively.