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Kinetics studies of nano-structured cobalt–manganese oxide catalysts in Fischer–Tropsch synthesis
Mohsen Mansouri,Hossein Atashi,Farshad Farshchi Tabrizi,Ali Akbar Mirzaei,Ghobad Mansouri 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4
The nano-structured cobalt/manganese oxide catalyst was prepared by thermal decomposition of [Co(NH3)4CO3]MnO4 precursor, and was tested for the Fischer–Tropsch reaction (hydrocarbon forming)in a fixed-bed micro-reactor. Experimental conditions were varied as follow: reaction pressure 1–10 bar,H2/CO feed ratio of 1–2 and space velocity of 3600 h1 at the temperature range of 463.15–523.15 K. On the basis of carbide and/or enolic mechanisms and Langmuir–Hinshelwood–Hougen–Watson (LHHW)type rate equations, 30 kinetic expressions for CO consumption were tested and interaction between adsorption HCO and dissociated adsorption hydrogen as the controlling step gave the most plausible kinetic model. The kinetic parameters were estimated with non-linear regression method and the activation energy was 80.63 kJ/mol for optimal kinetic model. Kinetic results indicated that in Fischer–Tropsch synthesis (FTS) rate expression, the rate constant (k) has been increased by decreasing the catalyst particle size. The catalyst characterization was carried out using different methods including powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurements.
M. Shiva,H. Atashi,F. Farshchi Tabrizi,A.A. Mirzaei 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.3
Combined UBI-QEP/LHHW methodology was employed for kinetic modeling of carbon monoxide hydrogenation to light olefins on a bimetallic Fe–Co catalysis in a fixed bed micro-reactor. In combination with apparent activation energies obtained from UBI-QEP approach, the experimental data from central composite designs were employed to fit several LH/ER rate equations. A new rate equation for CO consumption and a new mechanism based on parallel formyl/carbide with two RDS elementary reactions was concluded. It was also concluded that CO* is MARI on Fe–Co catalysis surface and its coverage on the catalyst was estimated to be 0.5 ml.
Mehdi Shiva,Hossein Atashi,Farhad Farshchi Tabrizi,Ali Akbar Mirzaei,Maryam Arsalanfar 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.1
The study addresses an enhanced approach for study of kinetics and mechanism of CO hydrogenation over Fe–Co catalyst. Kinetic models for rate of methane, paraffin and olefin formation have been developed by LHHW approach and information that obtained from UBI_QEP calculations.
Alaleh Dabbaghi,Ali Ramazani,Negin Farshchi,Aram Rezaei,Ali Bodaghi,Sobhan Rezayati 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.101 No.-
During the past decades, amphiphilic hydrogels found versatile applications in biomaterial field due totheir suitable mechanical properties and control on releasement of hydrophobic substrates. Polyethylene glycol (PEG) and polycaprolactone (PCL) are FDA approved polymers that were usedtogether in lots of research articles due to their complementary properties. This review focused on syntheticmethods, physical, and mechanical properties as well as sol–gel-sol phase transition behavior ofamphiphilic hydrogels based on polyethylene glycol (PEG) and polycaprolactone (PCL). Physical hydrogelswere formed base on the hydrophobic interaction between copolymers of PCL and PEG or basedon supramolecular chemistry. Also, chemical hydrogels synthesized via free radical crosslinking andchemical coupling reaction between functionalized prepolymers. Both types of physical and chemicalhydrogels are biocompatible and biodegradable. Physical hydrogels are thermo-sensitive and were usedas injectable hydrogels that can be sensitive to pH or other triggers. In addition, chemical hydrogels couldbe used as tissue scaffolds according to their mechanical properties.
Hossein Atashi,Kazem Motahari,Farshad Farshchi Tabrizi,Farhad Fazlollahi,Majid Sarkari 대한화학회 2011 대한화학회지 Vol.55 No.1
The effect of Group I alkali acetate promoters on vinyl acetate (VA) synthesis was evaluated. Catalyst product selectivity and ethylene conversion are compared to the unpromoted catalyst in the fixed-bed reactor with oxidation reaction of ethylene and acetic acid in gaseous phase over Pd-Au/SiO_2 catalyst. It was found that: a) the promoters were stabilized on the catalyst surface, b) common effect for the alkali promoted Pd-Au catalysts increaseed in product selectivity and ethylene conversion compared to unpromoted catalyst (these effects increase from top to the bottom of Group I). These promoting effect is due to the common-ion effect of acetate, present in the reaction, resulting in an increase in the activity of the catalyst. In addition a complementary theory for the effect of Au in the structure of the catalyst is proposed the imposition of distribution of palladium particles through decreasing the particle’s diameter.
Atashi, Hossein,Motahari, Kazem,Tabrizi, Farshad Farshchi,Sarkari, Majid,Fazlollahi, Farhad Korean Chemical Society 2011 대한화학회지 Vol.55 No.1
비닐 아세트산염 합성에 대한 1족 알칼리금속 아세트산염의 촉진 효과를 조사하였다. Pd-Au/$SiO_2$ 촉매를 사용한 경우와 사용하지 않은 경우에 대해 에틸렌과 아세트산 간의 기체상 반응에 대해 생성물 선택성과 에틸렌 전환을 비교하였다. 촉진제가 촉매 표면을 안정화시켰으며, 생성물 선택성과 에틸렌 전환을 촉진하였다. 이 촉매 효과는 1족에서 위에서 아래로 내려갈수록 증가하였다. 이것은 아세트산염의 공통이온효과 때문이다. The effect of Group I alkali acetate promoters on vinyl acetate (VA) synthesis was evaluated. Catalyst product selectivity and ethylene conversion are compared to the unpromoted catalyst in the fixed-bed reactor with oxidation reaction of ethylene and acetic acid in gaseous phase over Pd-Au/$SiO_2$ catalyst. It was found that: a) the promoters were stabilized on the catalyst surface, b) common effect for the alkali promoted Pd-Au catalysts increaseed in product selectivity and ethylene conversion compared to unpromoted catalyst (these effects increase from top to the bottom of Group I). These promoting effect is due to the common-ion effect of acetate, present in the reaction, resulting in an increase in the activity of the catalyst. In addition a complementary theory for the effect of Au in the structure of the catalyst is proposed the imposition of distribution of palladium particles through decreasing the particle's diameter.
Carbon Nanotube Reinforced Hybrid Microgels as Scaffold Materials for Cell Encapsulation
Shin, Su Ryon,Bae, Hojae,Cha, Jae Min,Mun, Ji Young,Chen, Ying-Chieh,Tekin, Halil,Shin, Hyeongho,Farshchi, Saeed,Dokmeci, Mehmet R.,Tang, Shirley,Khademhosseini, Ali American Chemical Society 2012 ACS NANO Vol.6 No.1
<P>Hydrogels that mimic biological extracellular matrix (ECM) can provide cells with mechanical support and signaling cues to regulate their behavior. However, despite the ability of hydrogels to generate artificial ECM that can modulate cellular behavior, they often lack the mechanical strength needed for many tissue constructs. Here, we present reinforced CNT–gelatin methacrylate (GelMA) hybrid as a biocompatible, cell-responsive hydrogel platform for creating cell-laden three-dimensional (3D) constructs. The addition of carbon nanotubes (CNTs) successfully reinforced GelMA hydrogels without decreasing their porosity or inhibiting cell growth. The CNT–GelMA hybrids were also photopatternable allowing for easy fabrication of microscale structures without harsh processes. NIH-3T3 cells and human mesenchymal stem cells (hMSCs) readily spread and proliferated after encapsulation in CNT–GelMA hybrid microgels. By controlling the amount of CNTs incorporated into the GelMA hydrogel system, we demonstrated that the mechanical properties of the hybrid material can be tuned making it suitable for various tissue engineering applications. Furthermore, due to the high pattern fidelity and resolution of CNT incorporated GelMA, it can be used for <I>in vitro</I> cell studies or fabricating complex 3D biomimetic tissue-like structures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2012/ancac3.2012.6.issue-1/nn203711s/production/images/medium/nn-2011-03711s_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn203711s'>ACS Electronic Supporting Info</A></P>