Catalyst

nassar's picture

Iron Oxide Nanoparticles for Rapid Adsorption and ‎Enhanced Catalytic Oxidation of Thermally Cracked ‎Asphaltenes

Journal Title, Volume, Page: 
Fuel Volume 95, Pages 257–262
Year of Publication: 
2012
Authors: 
Nashaat N. Nassar
Department of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada T2N 1N4
Current Affiliation: 
Department of Chemical Engineering, Faculty of Engineering and Information Technology, An-Najah National University, Nablus, Palestine
Azfar Hassan
Department of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada T2N 1N4
Francisco Lopez-Linares
Department of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada T2N 1N4
Pedro Pereira-Almao
Department of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada T2N 1N4
Preferred Abstract (Original): 

Thermally cracked asphaltenes from Athabasca vacuum residue produced at four different process severities were investigated for adsorption and subsequent catalytic oxidation. Fe3O4 nanoparticles were used for the removal of these four different thermally cracked asphaltenes from toluene solutions by a batch-adsorption technique followed by subsequent catalytic oxidation. Asphaltene adsorption kinetics and isotherms are presented. Further, the catalytic effect of nanoparticles on asphaltene oxidation has been addressed. Adsorption was rapid as equilibrium was achieved within 10 min. The equilibrium adsorption data fit well to the Langmuir model. It was found that the adsorption rate, affinity and capacity depend on the molecular weight (MW) of the asphaltenes. Adsorption rate and capacity were highest for the lower MW molecules while adsorption affinity was strongest for the larger MW molecules. In addition, in the absence of nanoparticles, the four thermally cracked asphaltenes oxidized differently. However, when adsorbed onto Fe3O4 nanoparticles their oxidation behavior became similar, showing the enhanced catalytic effect of nanoparticles.


Hikmat S. Hilal's picture

Dehydrocyclization of n-Hexane over Heteropolyoxometalates Catalysts

Journal Title, Volume, Page: 
Advances in Chemical Engineering and Science, 2013, 3, 82-92
Year of Publication: 
2013
Authors: 
H. S. Hilal
SSERL, An-Najah N. University, Nablus, Palestine
Current Affiliation: 
Department of Chemistry, An-Najah N. University, Nablus, PO Box 7, West Bank, Palestine
A. Eid
O. Benlounes
C. Rabia
S. Hocine
Preferred Abstract (Original): 
The catalytic dehydrocyclization of n-hexane was studied here for the first time using a number of compounds based on H3PMo12O40. The described catalysts were prepared by either replacing the acidic proton by with counter-ions such as ammonium or transition metal cations (NH4 +, Fe3+,K+), or by replacing Mo6+ with (Ni3+, Co3+, Mn3+) in the polyoxometalate framework, as reported earlier. For comparison purposes, the known (TBA)7PW11O39 catalyst system was used. All reactions were conducted at different temperatures in the range 200-450°C. The Keggin structure of these heteropolycompounds was ascertained by XRD, UV and IR measurements. 31P NMR measurements and thermal behaviour of the prepared catalysts were also studied. These modified polyoxometalates exhibited heterogeneous super-acidic catalytic activities in dehydrocyclization of n-hexane into benzene, cyclohexane, cyclohexene and cyclohexadiene. The catalysts obtained by substituting the acidic proton or coordination atom exhibited higher selectivity and stability than the mother parent compound H3PMo12O40. Catalytic activity and selectivity were heavily dependent on the composition of the catalyst and on the reaction conditions. At higher temperatures, the catalyst exhibited higher conversion efficiency at the expense of selectivity. Using higher temperatures (>400oC) in the presence of hydrogen carrier gas, selectivity towards dehydrocyclization ceased and methane dominated. To explain the results, a plausible mechanism is presented, based on super-acidic nature of the catalyst systems. Keywords: dehydrocyclization; heteropolyacid; catalyst; n-hexane; Keggin ion .
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Effect of Microemulsion Variable on Copper Oxide Nanoparticle Uptake By AOT Microemulsions

Journal Title, Volume, Page: 
Journal of Colloid and Interface Science Volume 316, Issue 2, 15 December 2007, Pages 442-450
Year of Publication: 
2007
Authors: 
Nashaat N. Nassar
Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB, T2N 1N4, Canada
Current Affiliation: 
Department of Chemical Engineering, An-Najah National University, P.O. Box 7, Nablus, Palestine
Maen M. Husein
Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB, T2N 1N4, Canada
Preferred Abstract (Original): 
Ultradispersed metal oxide nanoparticles have applications as heterogeneous catalysts for organic reactions. Their catalytic activity depends primarily on their surface area, which in turn, is dictated by their size, colloidal concentration and stability. This work presents a microemulsion approach for in situ preparation of ultradispersed copper oxide nanoparticles and discusses the effect of different microemulsion variables on their stability and highest possible time-invariant colloidal concentration (nanoparticle uptake). In addition, a model which describes the effect of the relevant variables on the nanoparticle uptake is evaluated. The preparation technique involved solubilizing CuCl2 in single microemulsions followed by direct addition of NaOH. Upon addition of NaOH, copper hydroxide nanoparticles stabilized in the water pools formed in addition to a bulk copper hydroxide precipitate at the bottom. The copper hydroxide nanoparticles transformed with time into copper oxide. After reaching a time-independent concentration, mixing had limited effect on the nanoparticle uptake and particle size. Particle size increased with increasing the surfactant concentration, concentration of the precursor salt, and water to surfactant mol ratio; while the nanoparticle uptake increased linearly with the surfactant concentration, displayed an optimum with R and a power function with the concentration of the precursor salt. Surface areas per gram of nanoparticles were much higher than literature values. Even though lower area per gram of nanoparticles was obtained at higher uptake, higher surface area per unit volume of the reverse micellar system was attained. A model based on water uptake by Wisor type II microemulsions, and previously used to describe iron oxide nanoparticle uptake by the same microemulsions, agreed well with the experimental results.
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