Hydrocarbon fuels produced by catalytic pyrolysis of hospital plastic wastes in a fluidizing cracking process
ABSTRACT A mixture of post-consumer polyethylene/polypropylene/polystyrene (PE/PP/PS) with polyvinyl chloride (PVC) waste was pyrolyzed over cracking catalysts using a fluidizing reaction system operating isothermally at ambient pressure. The influences of catalyst types and reaction conditions including reaction temperatures, ratios of catalyst to plastic feed, flow rates of fluidizing gas and catalyst particle sizes were examined. Experiments carried out with various catalysts gave good yields of valuable hydrocarbons with differing selectivity in the final products dependent on reaction conditions. A model based on kinetic and mechanistic considerations associated with chemical reactions and catalyst deactivation in the acid-catalyzed degradation of plastics has been developed. The model gives a good representation of experimental results from the degradation of commingled plastic waste. The results of this study are useful for determining the effects of catalyst types and reaction conditions on both the product distribution and selectivity from hospital plastic waste, and especially for the utilization of post-use commercial FCC catalysts for producing valuable hydrocarbons in a fluidizing cracking process.
SourceAvailable from: Waqas Ahmad[Show abstract] [Hide abstract]
ABSTRACT: Pyrolysis of polypropylene (PP) and high density polyethylene (HDPE) into fuel like products was investigated over temperature range of 250 to 400 °C. The product yields as a function of temperature were studied. Total conversion as high as 98.66 % (liquid; 69.82%, gas; 28.84%, and residue; 1.34 %) was achieved at 300 °C in case of PP and 98.12 % (liquid; 80.88 %, gas; 17.24 %, and residue; 1.88 %) in case of HDPE at 350 °C. The liquid fractions were analyzed by FTIR and GC-MS. The results showed that the liquid fractions consisted of a wide range of hydrocarbons mainly distributed within the C6–C16. The liquid product obtained in case of PP is enriched in the naphtha range hydrocarbons. Similarly, the liquid product obtained in case of HDPE is also enriched in naphtha range hydrocarbons with preponderance in gasoline and diesel range hydrocarbons. The % distribution of paraffinic, olefinic, and naphthenic hydrocarbons in liquid product derived from PP is 66.55, 25.7, and 7.58 %, respectively, whereas in case HDPE, the % distribution is 59.70, 31.90, and 8.40 %, respectively. Upon comparing the hydrocarbon group type yields, PP gave high yield of paraffinic hydrocarbons while HDPE gave high yields of olefins and naphthenes. The whole liquid fractions and their corresponding distillates fractions were also analyzed for fuel properties. The results indicated that the derived liquid fractions were fuel-like meeting the fuel grade criteria.International Journal of Green Energy 03/2014; 12(7):140303064405005. DOI:10.1080/15435075.2014.880146 · 1.47 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Thermogravimetric study of medical transfusion tube (MTT) waste containing polyvinyl chloride (PVC) was carried out using the thermogravimetric analyser (TGA) with N2, at different heating rates of 5, 10, 20, 30, 50 °C/min. The purpose is to obtain pyrolysis characteristics and kinetic parameters of medical waste. The experimental results indicate that the pyrolysis behavior of the MTT sample is in agreement with its main ingredient of PVC, appearing two stair stepping stages. The influence of the additives in MTT on pyrolysis behavior was also revealed, which could improve MTT pyrolysis at lower temperature in the first stage, and cause obvious unsmoothness and asymmetry of the second DTG peak. Four n-order kinetic models of Coats-Redfern, Ozawa, Kissinger and Freeman-carroll were used to get the kinetic parameters. Furthermore, a novel “two-step four-reaction model” was established to simulate the whole continuous process. The different methods and the kinetic parameters thus obtained were discussed and compared with each other in literatures. The reasons of deviation among kinetic values were tried to be elucidated. The new established model could more satisfactorily describe the pyrolysis process of MTT, being more mechanistic and conveniently serving for the engineering.03/2014; 21(3):1034-1043. DOI:10.1007/s11771-014-2034-0
[Show abstract] [Hide abstract]
ABSTRACT: Factorial Design Methodology (FDM) was developed to enhance diesel fuel fraction (C9–C23) from waste high-density polyethylene (HDPE) and Heavy Gas Oil (HGO) through co-pyrolysis. FDM was used for optimization of the following reaction parameters: temperature, catalyst and HDPE amounts. The HGO amount was constant (2.00 g) in all experiments. The model optimum conditions were determined to be temperature of 550 °C, HDPE = 0.20 g and no FCC catalyst. Under such conditions, 94% of pyrolytic oil was recovered, of which diesel fuel fraction was 93% (87% diesel fuel fraction yield), no residue was produced and 6% of noncondensable gaseous/volatile fraction was obtained. Seeking to reduce the cost due to high process temperatures, the impact of using higher catalyst content (25%) with a lower temperature (500 °C) was investigated. Under these conditions, 88% of pyrolytic oil was recovered (diesel fuel fraction yield was also 87%) as well as 12% of the noncondensable gaseous/volatile fraction. No waste was produced in these conditions, being an environmentally friendly approach for recycling the waste plastic.Waste Management 12/2014; 36. DOI:10.1016/j.wasman.2014.11.023 · 3.16 Impact Factor