STUDY OF SOME POTENTIAL PETROCROPS FOR LIQUID FUELS

Abstract

The world demand of petroleum products has been growing at a rate higher than the discovery of new resources in the last decade. If the demand rates sustain and if they are possibly met with by increased production, it is estimated that the worlds' presently recoverable oil sources would be exhausted before 2020. Thus, the search for alternative sources of hydrocarbons or similar chemicals has been started the world over in right earnest. Several directions are being explored. An important one amongst these is the possibility of deriving hydrocarbon type substances from renewable plant materials. The best solar energy converting machine available today is the green plant. Most plants store their energy as carbohydrates in the form of sugar or polymerised sugar (cellulose), but some plants store their energy as fully reduced carbon in the form of hydrocarbons. The most common example is the rubber tree, Hevea brasiliensis which produce hydrocarbons with a high molecular weight range (500,000 to 2,000,000). There are number of green plants which systhesize reduced constituents, having lower molecular weight than Hevea. If a source plant can be found, developed and cultivated which gives a liquid sap containing hydrocarbon type molecules or molecules predominantly of a type and size range which can be converted to liquid hydrocarbon type fuels. It offers a good route for deriving liquid fuels in quantities sufficient to replace petroleum derived fuels. This thesis covers study of some of the indigenous laticiferous and resinous species to assess their suitability as potential petrocroDS and conversion studies of biocrudes of some potential species to liquid fuels by Fluidized Catalytic Cracking. The work carried out has been presented as follows. In Chapter 1, the need to look for various alternative sources as substitutes for petroleum derived fuels and the importance of biomass as a possible renewable resource for liquid fuels is highlighted. A brief review of the research work carried out on potential petrocrops is also presented. This chapter in addition, covers screening of selected indigenous laticiferous species for their potential as petrocrops. Chapter 2, covers the evaluation of potential species by solvent extractions. Two solvent systems, hexane-methanol and naphtha-methanol were used to estimate their biocrude and polar contents. Biocrudes of 8 laticiferous species from the families of Euphorbiaceae and Asclepiadaceae were characterized by elemental analysis, molecular weight and iodine value determination. Studies on effect of ecological variation and age of the plant at the time of harvesting on its biocrude potential are also covered. The possible utilization ofE.antisyphilitica bagasse for paper making is explored by proximate chemical analysis. Conversion of 8 laticiferous biocrudes to liquid fuels byFluidized Catalytic Cracking under ASTM conditions and yields of various products such as gases, liquid fractions (35-200 °C, 200-245 °C and 245 °C+) and coke are presented. Optimization of reaction conditions to increase the liquid products yield and conversion results under optimized conditions are also given in Chapter 3. Chapter 4, presents the study carried out on indigenous resinous species. It includes, screening of these resinous species for their potential as petrocrops, estimation of biocrude contents of 6 species on dry weight basis, and conversion of 2 biocrudes to liquid fuels under ASTM conditions. Results of conversion of 6ofthese biocrudes to liquid fuels under optimized conditions are also presented.