Selhan Karagöz

Activated carbons from waste biomass by sulfuric acid activation and their use on methylene blue adsorption

Preparation of the activated carbons from sunflower oil cake by sulphuric acid activation with different impregnation ratios was carried out. Laboratory prepared activated carbons were used as adsorbents for the removal of methylene blue (MB) from aqueous solutions. Liquid-phase adsorption experiments were conducted and the maximum adsorption capacity of each activated carbon was determined. The effects of various process parameters i.e., temperature, pH, initial methylene blue concentration, contact time on the adsorption capacity of each activated carbon were investigated. The kinetic models for MB adsorption onto the activated carbons were studied. Langmuir isotherm showed better fit than Freundlich isotherm for all activated carbon samples. The rates of adsorption were found to conform to the pseudo-second-order kinetics with good correlation. The separation factor (R(L)) revealed the favorable nature of the isotherm of the MB activated carbon system.

Preparation and characterization of activated carbon from waste biomass.

Lignocellulosic materials are good and cheap precursors for the production of activated carbon. In this study, activated carbons were prepared from the pyrolysis of soybean oil cake at 600 and 800 degrees C by chemical activation with K(2)CO(3) and KOH. The influence of temperature and type of chemical reagents on the porosity development was investigated and discussed. K(2)CO(3) was found more effective than KOH as a chemical reagent under identical conditions in terms of both porosity development and yields of the activated carbons. The maximum surface area (1352.86 m(2)g(-1)) was obtained at 800 degrees C with K(2)CO(3) activation which lies in the range of commercial activated carbons. Elemental analyses of the activated carbons indicate insignificant sulphur content for all activated carbons. The ash and sulphur contents of the activated carbons obtained with chemical activation by K(2)CO(3) were lower than those by chemical activation with KOH.

Liquefaction of municipal waste plastics in VGO over acidic and non-acidic catalysts

Co-processing of municipal waste plastics (MWP) with vacuum gas oil (VGO) over HZSM-5, DHC-8 (commercial silica –alumina catalyst) and cobalt loaded active carbon catalyst has been comparatively studied. Co-processing experiments were carried out under hydrogen atmosphere at temperatures between 425 and 450 8C. The composition, sulphur and chlorine amount of liquid products were determined. The product distribution and the composition of liquids were changed depending upon the temperature and the catalyst type. As expected temperature led to increase in cracking activity of catalysts. DHC-8 and HZSM-5 showed substantially different activities in coprocessing due to the difference in their acidity. HZSM-5 gave highest gas yield at all temperatures and highest liquid yield (38.3) at low temperature. Although Co-AC was a neutral catalyst, it showed the cracking activity as well as HZSM-5 and more than DHC-8. No chlorine compound was observed in liquid products. The sulphur amount in liquid products varied with the catalyst type. Although HZSM-5 showed good cracking activity at low temperatures, it gave the liquid product containing highest sulphur amount. By considering both the quantity and quality of liquid fuel obtained from co-processing, it may be concluded that Co-AC gave the best result in the co-processing of the MWP/VGO blend. To observe the effect of metal type loaded on active carbon on catalyst activity, a series of co-processing experiments was also carried out. q 2002 Published by Elsevier Science Ltd.

Catalytic and thermal degradation of high-density polyethylene in vacuum gas oil over non-acidic and acidic catalysts

Abstract In this study, the conversion of HDPE in VGO to fuels was carried out in absence and presence of catalyst. The blend containing 20% HDPE was co-processed in presence of hydrogen at the temperatures of 435 and 450xa0°C. Five kinds of metal supported on active carbon catalysts (M-Ac) and acidic catalysts (HZSM-5 and DHC-8) were tested. The product distribution and the quality of liquid product changed depending upon the temperature and the type of catalyst. Among the metal supported active carbon catalyst, Co-Ac showed the highest cracking activity where as Mo-Ac showed the highest hydrodesulfurization activity. Co-Ac had better cracking activity than commercial hydrocracking catalyst (DHC-8). Although HZSM-5 had the best cracking effect in the hydrocracking of HDPE/VGO blend, the liquid product from HZSM-5 contained the highest sulphur. The use of carbon-supported metal catalysts in the co-processing of HDPE with VGO looks promising solution from an environmental viewpoint.

Conversion of polymers to fuels in a refinery stream

Abstract The purpose of this study was to investigate the processability of LDPE, PP, PVC/LDPE and PVC/PP in the hydrocracking unit of a refinery. For this, LDPE or PP has been added to vacuum gas oil (VGO). The blends were hydrocracked over different catalysts using a batch autoclave at 425–450xa0°C under hydrogen atmosphere. The catalysts used were HZSM-5, Cobalt loaded active carbon (Co-Ac) and DHC-8 (commercial silica-alumina catalyst). Addition of polymer to VGO affected the cracking of VGO, leading to a decrease in the gas yield and an increase in the liquid yield. In hydrocracking over HZSM-5, the product distribution was similar for two blends. HZSM-5 gave higher gas yields than the other catalysts. When using Co-Ac and DHC-8 catalysts, the gas and liquid yields depend on the polymer type as well as temperature. In the case of the PVC-containing blends (PVC/PP/VGO or PVC/PE/VGO), the blends were firstly dechlorinated at 350xa0°C. Then the dechlorinated mixture was hydrocracked in the 400–450xa0°C range in the presence of DHC-8. HCl evolved by degradation of PVC during the dechlorination step partially degraded PE and PP and these predegraded polymers were more easily cracked in the hydrocracking step. In addition, we observed the effect of polyene formed from the PVC degradation residue on the thermal hydrocracking. The chlorine compounds in the hydrocracked feed affected the catalytic activity of the catalysts.

Upgrading Scrap Tire Derived Oils Using Activated Carbon Supported Metal Catalysts

Abstract Scrap tire derived oils were upgraded over metal-loaded activated carbon catalysts and commercial catalyst at different operating conditions. Activated carbon support was prepared from the pyrolytic carbon black from pyrolysis of scrap tires. Activated carbon catalysts contained the metal pairs of Co-Ni, Co-Mo, and Ni-Mo. All metal-loaded activated carbon catalysts showed similar catalytic activity for upgrading process at 350°C under hydrogen pressure of 7 MPa. However, Ni-Mo/Ac showed good catalytic activity. Liquid fuels from upgrading oils over Ni-Mo/Ac and commercial catalyst containing 45–55% of naphtha fraction, 20–25% of kerosene fraction was obtained 350°C under hydrogen pressure of 7 MPa.