Showing papers by "Ravikrishnan Vinu published in 2015"

Bio-Oil Production from Prosopis juliflora via Microwave Pyrolysis

Abstract: Microwave pyrolysis is an efficient technique to valorize the abundantly available Prosopis juliflora (PJF) biomass into fuel intermediates. In this study, the effects of microwave power, susceptor...

Bio-oil production via catalytic microwave pyrolysis of model municipal solid waste component mixtures

Abstract: In this study, microwave assisted co-pyrolysis of mixtures of cellulose, paraffin oil, kitchen waste and garden waste that closely mimic municipal solid wastes (MSW) is conducted at different reaction conditions. Experiments were conducted in a multimode microwave reactor using ten different microwave absorbing materials (or susceptors) such as aluminium, activated carbon, garnet, iron, silica beads, cement, SiC, TiO2, fly ash and graphite. Pyrolysis was conducted up to 600 °C, and the effects of feed to susceptor ratio and composition of the model MSW mixture on (i) overall bio-oil, gas and char yields, (ii) heating value of the bio-oil, and (iii) composition of the bio-oil and gases, were evaluated. Besides greatly affecting the yields of bio-oil, gases and char, the susceptors played a catalytic role in altering the selectivity of the various components in bio-oil. The bio-oil contained oxygenated compounds (furans, phenolics, cyclo-oxygenates), aliphatic and aromatic hydrocarbons (mono and polycyclics). Aromatic hydrocarbons were the key products of interaction among the model components. Highest bio-oil yield of 53 wt% was achieved with an equal composition mixture at 1 : 1 wt/wt of MSW : graphite. This corresponded to nearly 95% energy recovery and 85% deoxygenation in bio-oil. High selectivities of monoaromatics such as benzene, toluene, xylene and styrene, and C8–C20 aliphatic hydrocarbons, and low selectivity of polycyclic aromatics were obtained with a majority of the susceptor–MSW combinations. Methane, ethylene, propylene, isobutylene and hydrogen were the major gaseous products, whose selectivities varied with MSW composition. This study shows that microwave assisted pyrolysis is a promising strategy to derive value added organics from MSWs.

Characterization of Thermal Stability of Synthetic and Semi-Synthetic Engine Oils

Abstract: Engine oils undergo oxidative degradation and wears out during service. Hence it is important to characterize ageing of engine oils at different simulated conditions to evaluate the performance of existing oils and also design new formulations. This work focuses on characterizing the thermo-oxidative degradation of synthetic and semi-synthetic engine oils aged at 120, 149 and 200 °C. Apparent activation energy of decomposition of aged oils evaluated using the isoconversional Kissinger-Akahira-Sunose technique was used as a thermal stability marker. The temporal variation of stability at different ageing temperatures was corroborated with kinematic viscosity, oxidation, sulfation and nitration indices, total base number, antiwear additive content and molecular structure of the organic species present in the oils. At the lowest temperature employed, synthetic oil underwent higher rate of oxidation, while semi-synthetic oil was stable for longer time periods. At higher temperatures, the initial rate of change of average apparent activation energy of synthetic oil correlated well with a similar variation in oxidation number. A mixture of long chain linear, branched, and cyclic hydrocarbons were observed when semi-synthetic oil was degraded at higher temperatures.

Fast co-pyrolysis of cellulose and polypropylene using Py-GC/MS and Py-FT-IR

Abstract: In this study, the production of high quality biofuel intermediates via fast co-pyrolysis of cellulose and polypropylene (PP) is investigated. Fast co-pyrolysis experiments were performed in a Pyroprobe® reactor and the generated vapors were analyzed using a gas chromatograph-mass spectrometer for the composition of pyrolysates, and Fourier transform infrared spectrometer for the time evolution of the key functional groups. The effects of cellulose : PP mass ratio (100:0, 75:25, 50:50, 25:75, 0:100) and temperature (500–800 °C) on bio-oil composition, carbon number distribution of the products, higher heating value of the products, and temporal evolution of O–H, C–O, –CH2–, CO2 and CO groups were evaluated. Formation of long chain alcohols in the carbon number range of C8–C20 was observed as a result of the interaction of cellulose and PP. Feed composition played a decisive role in the formation of alcohols and hydrocarbons. A maximum of ca. 36% alcohols and 45% hydrocarbons were obtained from PP-rich mixture at 600 °C. The yield of char decreased and that of the aromatic hydrocarbons increased with pyrolysis temperature. Significant improvement in the heating value of the products was observed when PP was blended with cellulose. Importantly, the calculated heating values correlated well with the cumulative content of alcohols, aliphatic and aromatic hydrocarbons. The addition of PP to cellulose significantly decreased the time taken for completion of pyrolysis. Based on the product distribution, hydroxyl, hydrogen and methyl abstraction were found to be the dominant reactions involved in the transformations.