S. K. Maity

Characterization and evaluation of ZrO2 supported hydrotreating catalysts

A series of zirconia supported molybdenum catalysts were prepared and characterized by BETSA, XRD, TPR, FTIR, XPS and oxygen chemisorption. Thiophene, cyclohexene and tetrahydrofuran were taken as model compounds for evaluating their hydrodesulfurization (HDS), hydrogenation (HYD) and hydrodeoxygenation (HDO) activities, respectively. The XRD results indicate that Mo is present as a monolayer up to 6 wt.% loading, whereas MoO3 crystalline growth is observed beyond this loading. O2-uptake and catalytic activities also increase up to 6 wt.% Mo-loading but above this loading both start decreasing. There are good correlations between O2 uptake and all catalytic activities. TPR and FTIR results indicate that at lower loading, MoO3 is present as tetrahedra form and at moderate loading, both tetrahedral and octahedral forms are found. XPS results reveal that the electron transfer is taking place from support to molybdenum.

Characterization and hydrodesulfurization catalysis on WS2 supported on mesoporous Al-HMS material

Abstract Hexagonal mesoporous silica (HMS) and Al–HMS materials with high surface area and mesoporous structure were synthesized following the neutral templating path way. These materials were used as a support for the first time in preparing W/HMS, and W/Al–HMS catalysts and their Co, and Ni promoted analogues. On Al–HMS support (Si/Al=35) the tungsten loading was varied from 10 to 25 wt.%. On a catalyst containing 21 wt.% W the promoter concentration was varied from 1 to 5 wt.%. Oxygen uptakes and crystallite sizes of WS 2 derived from it indicated that WS 2 is well dispersed at all the loadings studied. The hydrodesulfurization and hydrogenation activities varied in a similar manner to that of oxygen uptakes as a function of W loading indicating that there exists a correlation between oxygen chemisorption and catalytic sites. The HMS and Al–HMS mesoporous material supported WS 2 catalysts showed outstanding activities in comparison with WS 2 supported on γ-Al 2 O 3 .

Catalytic functionalities of TiO2 based SiO2, Al2O3, ZrO2 mixed oxide hydroprocessing catalysts

Thiophene HDS and cyclohexene HYD activities on three mixed oxides supported Mo and promoted by Co or Ni are presented. A comparative study indicated that Ti containing mixed oxide supports show outstanding activity for HDS. The trends of variation of activities indicated that the two functionalities originate from different set of catalytic sites on molybdenum sulfide phase.

Studies on sepiolite supported hydrotreating catalysts

Abstract Sepiolite is a hydrous magnesium silicate, receiving considerable attention in catalysis as support as well as catalyst. In this investigation a sepiolite was used as support for MoO 3 and the sulfided form used for hydrodesulfurization and hydrogenation reaction using thiophene and cyclohexene as model compounds respectively. The catalysts were characterized by surface area measurement, X-ray diffraction, IR and temperature programmed reduction methods. These results indicated that molybdenum is present as a monolayer upto 6 wt.% Mo loading and beyond this loading MoO 3 crystallite growth is observed. The low temperature oxygen chemisorption results indicated that there is no crystallite growth upto the monolayer region and beyond this there is rapid growth of MoS 2 crystallites. It was proposed that molybdenum interacts with basic hydroxyl groups attached to support. Linear correlations passing through origin are obtained between catalytic activities for thiophene hydrodesulfurization or cyclohexene hydrogenation and oxygen uptakes indicating that the anion vacancies created on reductive sulfiding are the seat of catalytic activity. Since correlations are obtained in the case of both HDS and HYD it is clear that oxygen chemisorption is not specific to any one of the functionalities but measures anion vacancies which are related to the state of dispersion of molybdenum.

Support effect studies on Tio2-Al2O3 mixed oxide hydroprocessing catalysts

Abstract TiO 2 -Al 2 O 3 supports with varying TiO 2 /Al 2 O 3 ratios were synthesized by homogeneous precipitation technique and these supports were found to be of high surface area and reasonably high surface area is also obtained in the case of Co and Ni promoted catalysts. X ray diffraction data indicated that in titania rich regions anatase is observed and in γ-Al 2 O 3 rich region of mixed oxide presented anatase as well as γ-Al 2 O 3 peaks are noticed, where as a TiO 2 -Al 2 O 3 (5050) samples are nearly X-ray amorphous indicating that this region presents highly intimate mixture of TiO 2 and Al 2 O 3 . Except on TiO 2 supported system, there is no evidence for XRD for any crystalline phases of WO 3 indicating a good dispersion of WO 3 . The oxygen chemisorption measurements indicated that oxygen chemisorption passes through a maximum at TiO 2 -Al 2 O 3 (5050) support both on tungsten alone and Co Ni promoted catalysts. The Temperature Programmed Reduction studies indicated that on TiO 2 and TiO 2 rich TiO 2 -Al 2 O 3 mixed oxide supports the tungsten oxide interacts weakly with support compared to Al 2 O 3 and Al 2 O 3 rich TiO 2 -Al 2 O 3 supports where WO 3 is found to interact strongly. The catalytic activities for various catalytic functionalities such as Hydrodesulfurization (HDS) and Hydrogenation (HYD) were evaluated and the results indicated the pattern of activity variation is very similar to that of oxygen uptakes suggesting that there is a relationship between oxygen chemisorption and catalytic functionalities but lack of strictly linear relationship casts some doubts on the applicability of oxygen chemisorption catalysts prepared by varying the support. These results suggested that oxygen chemisorption is not specific to any one of the functionalities but measures general state of dispersion.

Use of Polymers/ Waste Rubber in Road Network Development in Uttarakhand State

Proper utilization of industrial polymer/waste tyre rubber are a major threat to environment specially in developing countries where poverty, population and lack of proper waste management have catalyzed this problem. Use of waste polymer like waste tyres in road construction has potential for utilization and disposal these waste polymers instead of non-environment friendly methods like burning and landfills. In this paper we have highlighted the use of polymeric material in scientific as well as eco-friendly point of new. The main focus of this paper is to review and discuss the feasibility for using polymer modified bitumen (PMB) for developing high performance road network in uttarakhand. The experimental results reported in this paper are taken from the test sections of polymer modified bituminous (PMB) road laid at delhi-yamanotri marg near Herbertpur under a joint project of Indian Institute Of Petroleum (CSIR-IIP) and central road research institute (CRRI). This polymer modified bituminous road in the state is first of its kind. Three commercially available modified binders crumb rubber modifier (CRM) styrene-butadiene-styrene (SBS) and ethylene butyl acrylate (EBA) were used for construction of test sections; which were compared for their performance. Various physical tests like elastic recovery, softening point, penetration, viscosity and fail temperatures were carried out on modified binders and post construction evaluation tests like unevenness index measurement and Benkelman Beam Deflection tests were carried out on test sections. The results show the improvement in engineering properties like marshall stability, retained stability of road compared to unmodified bituminous road in terms of traffic and weather conditions of Uttarakhand. The findings of this research can serve as the base for the use of other wastes from the industries in roads making technology on which the research is already in progress at CSIR-Indian Institute of Petroleum and CSIR-Central Road Research Institute.