توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Acidity deterioration and coke deposition on Iron– Zeolite Catalyst in Fischer – Tropsch Synthesis
اطلاعات انتشار: پنجمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۱۳
Considerable effort has been devoted in resent years to the investigation of bifunctional catalysts for the conversion of synthesis gas to selected product states, especially gasoline range hydrocarbons. The interest arises from the fact that the catalytic conversions of syngas to hydrocarbons over Fischer – Tropsch (FT) catalysts such as Fe and Co doesnot make liquid fuels with sufficient selectivity. The HZSM–5 supported iron catalyst have been investigated with respect to physical and chemical properties and to activity and product selectivity for conversion of syngas to hydrocarbon products. The catalyst preparation consisted of physical admixture of precipitated iron oxide with HZSM–5. Fe\Cu catalyst with different promoters consists of CaO, MgO and La2O3 was prepared by copercipitation technique and was added to HZSM–5 catalysts and then, mixed thoroughly with binders like Silica– Zirconium, Silica–titanium and Silica–Alumina and shaped to cylinders. Catalyst activity study was carried out in a fixed bed stainless still reactor at 290 oC, 17bar; H2\CO=1, GHSV=3.07 nl (g.Fe.h)–1 for time on stream 250 h. The acidity deterioration of the HZSM–5 from the iron – zeolite catalyst has been related to coke deposition. The effect of promoters and binders on coke deposition and acidity deterioration of the HZSM–5 has been studied from experiments in a fixed–bed reactor.<\div>

۲Deactivation behavior of Co–Ru\γ–Al2O3 Fischer–Tropsch synthesis catalyst along the catalytic bed
اطلاعات انتشار: ششمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۴
Deactivation of Ru–Co\γ–Al2O3 Fischer–Tropsch (FT) synthesis catalyst along the catalytic bed is investigated. Catalytic bed was divided into four parts and catalyst morphology changes were studied using BET, ICP, XRD, TPR, Carbon determination, H2 chemisorption and oxygen titration techniques. During the first 200 h, catalyst deactivation was rapid, zero order to %conversion and dependent on the size of active sites. When time exceeded 200 h the deactivation can be simulated with a power law expression: –dXCO\dt=kXCO 28.5. The skeleton of the catalyst charged in 1st half of the reactor did not change significantly. Interaction of cobalt with alumina and formation of mixed oxides of the form xCoO.yAl2O3 and CoAl2O4 was increased along the catalytic bed. Percentage reducibility for the catalyst in the beds 1 to 4 decreased by 2.4, 3.6, 13 and 25.5% and percentage dispersion decreased by 0.5, 1.7, 2.8 and 8.8% for the catalyst in the beds 1 to 4 respectively. Particle diameter increased by 0.8, 1.3, 2.8 and 6.1% for the catalyst in the beds 1 to 4 respectively suggesting higher rate of sintering at last catalytic bed. The amount of coke formation in the 4th catalytic bed was 6 times more than that of in bed 1.<\div>

۳Effect of electronic properties of Carbon Nanotubes on the Activity, Selectivity and Lifetime of Fischer–Tropsch Co\CNTs Catalysts
نویسنده(ها):
اطلاعات انتشار: چهاردهمین همایش بین المللی نفت، گاز و پتروشیمی، سال
تعداد صفحات: ۳۴
The effects of electronic properties of inner and outer surfaces of carbon nanotubes CNTs on the deactivation of cobalt. Fischer –tropsch FT catalysts were studied. The comparative characterization of the fresh and used catalysts by TEM,XRD,TPR,BET and H2 chemisorption showed that cobalt re – oxidation , cobalt –support interactions and sintering are the main sources of catalyst deactivation. TEM showed that 480 h continuous FT synthesis increased the average particles size of the particles located inside the pores from 7 to 7.4 nm while the average particles size of the particles located outside of the tubes increased from 11.5 to 25nm.XRD analysis of the used catalyst confirmed cobalt re–oxidation and interatcion between cobalt and CNTs and creation of carbide phases. when the co% conversion and H2O partial pressure in the reactor are high, the deactivation rate is not dependent on the number of the catalyst active sites and is zero order to %CO conversion.<\div>

۴Sustainable Hydrogen Production via Supercritical Water Gasification of Agricultural Wastes
نویسنده(ها): ، ،
اطلاعات انتشار: کنفرانس بین المللی توسعه پایدار، راهکارها و چالش ها با محوریت کشاورزی ، منابع طبیعی، محیط زیست و گردشگری، سال
تعداد صفحات: ۷
Biomass is an available and renewable resource that can be converted to valuable biofuels like bio ethanol and bio–hydrogen to supply future energy demand and reaching sustainable energy development objectives. Agricultural residues are valuable feed stocks that hundreds of thousands tons of it is burned annually in the lack of conversional industries in Iran. Gasification of biomass in supercritical water media is a promising technology to convert bio–products into useful fuels such as hydrogen as an energy carrier. In this article we studied the conversion of wheat straw, walnut shell and almond shell into the hydrogen. Hydrogen gas yields of 6.52, 4.26 and 4.1 mmoles were observed for the gasification of 1 gram of wheat straw, walnut shell and almond shell respectively, in a batch micro reactor. It was also observed that wheat straw had 42.6% and 46.9% hydrogen and carbon gasification efficiency respectively, which was the highest among the others. Furthermore, according to the structural analysis, it was recognized that biomasses with higher cellulose and hemicellulose and lower lignin contents were better gasified due to their higher and easier solubility and hydrolysis in water.<\div>

۵Modified γ–Al2O3 and its application for FT synthesis
نویسنده(ها): ، ، ،
اطلاعات انتشار: پانزدهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۵
In this research, γ–Alumina was pretreated in the presence of phosphoric acid–ethanol, and then used to prepare the supported cobalt catalysts for Fischer–Tropsch synthesis (FTS). Different concentrations of phosphoric acid were applied for pretreatment of γ–Alumina to modify it's surface properties. The catalysts were prepared by incipient wetness impregnation of the cobalt precursor, and deionized water was used as preparation medium. The reduction degree and dispersion of γ–alumina–supported cobalt catalyst were improved through this pretreatment. The obtained catalysts were characterized by FTIR, NH3–TPD, XRD, TPR, TEM and H2 chemisorption. These characterizations clearly showed the changesof morphology (surface area, pore volume, pore size distribution and crystallite phase) as well as chemical properties (e.g. acidity) of the supports. Optimize the support pretreatment parameters exhibited significant catalyst's stability and activity, applying to FTS reaction in CSTR reactor during 320 h test.<\div>

۶Comparing the performance of Co\CNT and Co,Ru\CNT nano catalysts using microemulsion technique in Fischer– Tropsch synthesis
نویسنده(ها): ، ،
اطلاعات انتشار: پانزدهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۶
Cobalt and Bimetallic cobalt–ruthenium nano catalysts supported on carbon nanotubes (CNTs) are prepared using microemulsion technique with water to–surfactant ratios of 0.5−1.5. The nano catalysts were extensively characterized by different methods and their activity and selectivity in Fischer–Tropsch synthesis (FTS) have been assessed in a fixed–bed microreactor. The physicochemical properties and performance of the 15 wt% Co, 1 wt% Ru\CNT nanocatalysts were compared with the 15wt% Co\CNT nanocatalysts. the use of microemulsion technique with water to surfactant ratio of 0.5 decreased the average cobalt oxide particle size to 4.8–4.9 nm, the dispersion was almost doubled and the reduction increased . Ruthenium was found to enhance the reducibility of Co3O4 to CoO and that of CoO to Co0, increase the dispersion and decrease the average cobalt cluster size. Moreover 1 wt% Ru increased the FTS rate of 15 wt.%Co\CNT catalyst from 0.362 to 0.372 gHC\(gcat.h) and enhanced the selectivity of FTS towards the higher molecular weight hydrocarbons<\div>

۷Effects of particle size on the activity and product selectivity of Fe–Mn\CNTs nano catalyst
نویسنده(ها): ، ،
اطلاعات انتشار: پانزدهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۴
Bimetallic Fe–Mn nano catalysts supported on carbon nanotubes (CNTs) are prepared using microemulsion technique with water–to–surfactant ratios of 0.4–1.6. The nano catalysts were extensively characterized by different methods and their activity and selectivity in Fischer– Tropsch synthesis (FTS) have been assessed in a fixed bed micro–reactor. The physico–chemical properties and performance of the nanocatalysts were compared with the catalyst prepared by impregnation method. Very narrow particle size distribution has been produced by the microemulsion technique at the relatively high loading of active metal. Using microemultion technique with water to surfactant ratio of 0.4 decreased the average iron particle sizes to 5.7 nm. The percentage reduction and percentage dispersion are almost doubled. Activity and selectivity were found to be dependent on iron average particle sizes. The CO% conversion and FTS rate increased from 58.6 to 70.98% and 0.2 to 0.289 (gr. HC\gr. cat.\hr), respectively.While the WGS rate decreased from 0.08 to 0.056 (gr. CO2\gr. cat.\hr) and olefins\paraffins ratio incresed from 0.9 to 2 .<\div>

۸Activity and stability improvement of Cobalt nanocatalyst in Fischer–Tropsch synthesis by functionalized CNT
نویسنده(ها): ، ،
اطلاعات انتشار: پانزدهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۴
Common and nitrogen–doped carbon nanotubes as functionalized CNTs supported cobalt nanocatalysts were prepared using microemulsion technique with cobalt loading of 15 wt.%. Functionalization of carbon nanotubes (CNTs) was performed, to modify the surface properties of CNTs support. Samples were dried and reduced at 400 °C for 12 h, and then FT synthesis was carried out in a fixed–bed micro reactor. The FTS activity, selectivity and stability of the catalysts were evaluated and compared with the non–functioned CNT. The catalysts were characterized by Brunauer–Emmett–Teller (BET), X–ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. Results showed functioned CNT and microemulsion synthesis method lead to a better cobalt nanocatalyst. Cobalt nanocatalysts on N–doped CNTs which prepared by microemulsion method has lower average cobalt cluster size in comparison of common CNT as support. Additionally this catalyst shows well dispersion of the cobalt, and improved activity and stability of FTS. The proposed cobalt catalyst supported on functionalized CNTs increased the percentage CO conversion to 54%<\div>

۹Preparation of a Novel Super Active Fischer–Tropsch Cobalt Catalyst Supported on Carbon Nanotubes
نویسنده(ها):
اطلاعات انتشار: Iranian Journal of Chemistry and Chemical Engineering (IJCCE)، بيست و هشتم،شماره۱(پياپي ۴۹)، ۲۰۰۹، سال
تعداد صفحات: ۱۲

۱۰Optimization of energy consumption and offering a procedure for cooling gas compression facilities at gas compression stations
اطلاعات انتشار: Energy Equipment and Systems، سوم،شماره۲، Autumn ۲۰۱۵، سال
تعداد صفحات: ۱۲
One of the most important methods of transporting natural gas in Iran and other parts of the world is the utilization of a network of pipelines. Compression station and turbo compressor units play an important role in gas supply through pipelines. One of the primary concerns in these units is the reduction of fuel consumption. By cooling of exhaust gas from the source station, the pressure drop in the pipeline and fuel consumption can be reduced. In this research, two stations were investigated while ASPEN HYSYS software was used to evaluate the effect of various parameters on pipeline pressure and power compressors. Based on the results of the simulation, the cooling gas at a higher flow was more economical. Moreover, with reducing ambient temperature, there was a decrease in power consumption, which was required for electro fans. Thus, higher rates and lower temperatures of the environment resulted in more profit from cooling operations. Although highest economic efficiency was obtained at the highest flow rate (60 MMSCMD) with cooling at 25℃ and lowest ambient temperature of –8℃, but the conditions for hydrate formation in the pipeline became suitable and these conditions could affect the safety of process. In this study, and taking cognizance of the the limitations of hydrate formation and economic conditions, the cooling operational guidelines for use in Qazvin station are provided.

۱۱Size–dependent Kinetics Determination of MoS2–K2O\CNTS Nanocatalyst in the Synthesis of Alcohols from Syngas
نویسنده(ها): ، ،
اطلاعات انتشار: Journal of Petroleum Science and Technology، پنجم،شماره۱، ۲۰۱۵، سال
تعداد صفحات: ۱۳
The influence of Mo particle size on the catalytic activity and product selectivity of alkalized MoS2 nanocatalysts has been investigated. Nanocatalysts are prepared using a microemulsion technique with water–to–surfactant ratios of 1–12. Three different techniques, including XRD, TEM, and hydrogen chemisorption were used to determine the molybdenum average particle size and their activity and selectivity in higher alcohols synthesis (HAS) carried out in a fixed bed microreactor at 330 °C and 70 bar. To fix the percentage of CO conversion, the GHSV is changed from 3.6 to 2.57 (nl\(hr.g catalyst)). The average MoS2 particle sizes are changed from 4.5 to 11.9 nm. The experimental results showed that changing particle size from 11.9 to 4.5 nm decreased the methanol formation rate from 0.00634 to 0.00534 (mol\(hr.g catalyst)) but increased ethanol formation rate from 0.00581 to 0.00787 (mol\(hr.g catalyst)) and higher alcohols formation rate from 0.00473 to 0.00657 (mol\(hr.g catalyst)). A size–dependent kinetics model was developed to calculate the alcohol formation rates versus catalyst average particle size. The model not only matched experimental and theoretical results, but also showed that MoS2 catalyst had size–dependent structure and for the prediction of product selectivity it was easier to use this mathematical model.
نمایش نتایج ۱ تا ۱۱ از میان ۱۱ نتیجه