Cr Incorporated MCM-41 Type Catalysts for lsobutane Dehydrogenation and Deactivation Mechanism

2013-03-13
Kilicarslan, Saliha
DOĞAN, MELTEM
Doğu, Timur
Cr incorporated MCM-41 type catalysts, which were prepared by direct hydrothermal synthesis and impregnation routes, were tested for dehydrogenation of isobutane. Among the surfactants (C17H38BrN, C19H42BrN, and C32H68BrN) used in the synthesis of MCM-41, C19H42BrN gave the best structure with ordered mesopores. Characterization results proved that chromium was very well dispersed within the MCM-41 lattice of the synthesized catalysts. In all of the synthesized catalysts, the presence of Cr6+ (2p(3/2)) in the form of chromates and Cr3+(2p(1/2)) in the form of Cr Ox or Cr2O3 was detected. All chromate types (mono, di, and poly) were observed in the catalyst synthesized hydrothermally according to the addition of metal solution simultaneously with silica source (CR_ALS). All characterization methods demonstrated that the highest amount of Cr6+ was present in this catalyst. Catalytic tests of the synthesized catalysts were carried out at 600 C and at atmospheric pressure. The maximum conversion value (similar to 27%) was reached at 15 min on CR_ALS catalyst. No products other than isobutene and hydrogen were encountered at the reactor outlet. Results proved that coke deposition was negligible over the synthesized catalysts in isobutane dehydrogenation. It was shown that the monochromates were the most active phase among all types of chromates for isobutane dehydrogenation. Catalyst deactivation occurred when the tetrahedrally coordinated Cr(VI)04 type of chromate was converted to inactive octahedrally coordinated Cr(III)O-6 groups and Cr2O3 crystal phase.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH

Suggestions

Ni-MCM-41 type mesoporous catalysts synthesized by one-pot hydrothermal procedure for steam reforming of ethanol
Ozdogan, Ekin; Doğu, Timur; DOĞU, GÜLŞEN (2007-01-02)
In the present study, Ni incorporated MCM-41 structured mesoporous catalysts with a Ni/Si atomic ratio of 0.036 and 0.15 were prepared by a direct hydrothermal synthesis procedure. These catalysts had surface area values of 860.5 m(2)/g (Ni-MCM-41 having a Ni/Si ratio of 0.036) and 944.9 m(2)/g (Ni-MCM-41 having a Ni/Si ratio of 0.15). They also had narrow pore size distributions with average pore diameters of 2.7-2.6 nm respectively. Ni MCM-41 synthesized by the one-pot hydrothermal synthesis procedure sho...
Effects of synthesis conditions on the structure of Pd incorporated MCM-41 type mesoporous nanocomposite catalytic materials with high Pd/Si ratios
Sener, Canan; Doğu, Timur; Dogu, Gulsen (2006-09-08)
Pd incorporated MCM-41 type mesoporous catalytic materials were prepared by the basic and the acidic direct hydrothermal synthesis procedures using different Pd sources. Also, nanocomposite materials containing Pd nanoballs within the mesopores of the host MCM-41 were prepared following an impregnation procedure. Basic direct hydrothermal synthesis route was shown to be highly successful for the production of high surface area (over 1000 m(2)/g) Pd-MCM-41 nanocomposite materials with very high Pd/Si wt. rat...
Non-isothermal DSC and TG/DTG analysis of the combustion of silopi asphaltites
Kök, Mustafa Verşan (2007-06-01)
In this research, non-isothermal combustion and kinetics of Silopi (Turkey) asphaltite samples were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). A sample size of 10 mg, heating rates of 5, 10, 15 and 200C min(-1) were used in the temperature range of 20-600 degrees C, under air atmosphere. Two reaction regions were observed in DSC curves. The first region is due to the evaporation of moisture in asphaltite sample whereas, release of volatile matter and burning of ca...
Coke Minimization in Dry Reforming of Methane by Ni Based Mesoporous Alumina Catalysts Synthesized Following Different Routes: Effects of W and Mg
ARBAĞ, HÜSEYİN; YAŞYERLİ, SENA; YAŞYERLİ, NAİL; Doğu, Timur; DOĞU, GÜLŞEN (Springer Science and Business Media LLC, 2013-12-01)
Ni based mesoporous alumina (MA) catalysts were synthesized by sol-gel (SGA) and hydrothermal (MA) methods, following impregnation and one-pot synthesis routes and catalytic performances of these materials were tested in dry reforming of methane. Results proved the importance of synthesis procedure of the MA supports on the activity and coke resistance of the synthesized materials, containing 16 % Ni. Among these catalysts, MA prepared by the sol-gel technique (Ni@SGA) showed the highest activity in dry ref...
Direct hydrothermal synthesis of palladium-incorporated silicate-structured mesoporous catalysts
Sener, Canan; Doğu, Timur; Dogu, Guelsen (2007-01-01)
Pd-Si-structured novel mesoporous nanocomposite catalytic materials, having quite high Pd/Si ratios, were synthesized by an acidic direct hydrothermal synthesis route. The nanocomposite catalytic materials were then characterized by XRD, XPS, EDS, nitrogen adsorption, and SEM techniques. Unlike MCM-41, the XRD patterns indicated a rather wide d((100)) band at a 2 theta value of about 1.9. The materials, with very high Pd/Si wt ratios between 1.43 and 2.66, were synthesized and had BJH surface area values be...
Citation Formats
S. Kilicarslan, M. DOĞAN, and T. Doğu, “Cr Incorporated MCM-41 Type Catalysts for lsobutane Dehydrogenation and Deactivation Mechanism,” INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, pp. 3674–3682, 2013, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/31278.