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A CaO based catalyst synthesized from mortar previously used in construction was chosen for pyrolysis of LDPE plastic waste. The samples were calcined at temperatures of 500 and 800 °C for comparison purpose. After calcination, two mixed oxides were obtained, denoted as catalyst A and B. The chemical composition of the metal oxide catalysts and the liquid products of the pyrolysis were characterized by X-ray Fluorescence (XRF) and Simulated Distillation - Gas Chromatography (SD-GC), respectively. The XRF analysis indicated that the catalyst, reformed from the mortar cement, consisted of CaO, silica (silicon dioxide, SiO2) and alumina (aluminium (III) oxide, Al2O3) as the main constituents, though, the composition of each compound differed because of the influence of calcination temperature. Catalyst A had 41.96% of CaO, 4.27% of Al2O3 and 30.82% of SiO2 when the catalyst B had 37.04% of CaO, 2.38% of Al2O3 and 37.31% of SiO2. The amount of CaO in the catalyst B was found to be less in catalyst A. The catalyst A gave higher percentage yield of naphtha oil (48±1.14%v/v), compared to catalyst B (21±1.26%v/v). The performance of this catalyst (A) towards the pyrolysis of plastic wastes was compared to commercial grade ZSM-5 and FCC catalysts. It was found that the catalyst A, CaO based catalyst, reformed from the mortar cement, gave the highest yield of naphtha oil (48±1.14%v/v) compared to ZSM-5 (26±1.52%v/v) and FCC (16±1.09%v/v). The optimum operating temperature for the pyrolysis was found at 410 °C (in the temperature range 370 °C to 450 °C) and the optimum catalyst (A) composition was 0.3 %w/w of mortar cement catalyst in LDPE. This optimum condition gave 86.67± 0 %w/w of liquid, 12.49± 0.24 %w/w of gas and 0.84± 0.24 %w/w of solid. The catalyst A showed the best performance amongst all the catalysts towards the pyrolysis process of plastic wastes.

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The steam reforming of used lubricating oil (ULO) over Ni- and Rh-based catalysts supported by Ce-ZrO2 and Al2O3 is studied in the present work. Among all catalysts, Rh/Ce-ZrO2 (5 wt % Rh) provides relatively higher reforming reactivity (in terms of ULO conversion and H2 yield) with excellent resistance toward carbon deposition compared to the other three catalysts. At 850 °C after exposure in the steam reforming condition for 72 h, H2 yield of 78.1% can be achieved from the reaction over Rh/Ce-ZrO2. For Ni/Ce-ZrO2 and Ni/Al2O3, significant deactivations with time are detected and H2 yields of 55.3−58.7% are achieved after exposure for 72 h; in addition, considerable amounts of C2H4, C2H6 and C3H6 are also found in the product along with H2, CO, CO2, and CH4. The effect of O2 addition was further studied over Ni/Ce-ZrO2 and Ni/Al2O3. It was found that this addition significantly reduces the degree of carbon deposition as well as promoting the conversion of hydrocarbons to CO and H2. At a suitable amount of O2, a high H2 yield comparable to that of steam reforming over Rh-based catalysts can be achieved. Nevertheless, it must be noted that introducing too high an O2 content resulted in lower H2 production due to the combustion of H2 and ULO by O2 addition.