Contents - Akademi Sains Malaysia

ASM Sci. J., 7(1), 7–17Liquefaction of Mukah Balingian Coal via SemicontinuousTwo-stage Solvent Flow Reactor SystemM.A.M. Ishak 1 *, M.T. Safian 1 , Z.A. Ghani 1 and K. Ismail 1Solvent flow reactor system was introduced into the extraction system to increase the system efficiencyand enhance the extraction yield by adding fresh solvent during the extraction processes. The liquefactionexperiment was carried out at various flow-rates (1, 3 and 5 ml/min), reaction times (30, 45 and 60 min) andreaction temperatures (300ºC, 350ºC, 400ºC, 420ºC and 450ºC) with tetralin as solvent. Despite the abilityof adding fresh solvent into the extraction process, the conversion of oil+gas was still considered to be lowas there was ~25% of coal extracts left to be converted into low molecular weight compounds. One possibleoption to increase the oil yield is by applying catalyst that will further break up the coal extracts into smallmolecular weight compounds. In this study, a second reactor was introduced consisting of catalyst (NiSiO 2 )assuming that the catalyst would interact more effectively with coal extracts rather than the coal itself. In theabsence of catalyst, the oil yield was 55%. By introducing the Ni catalyst, the oil yield increased by 15%.Further analysis of GCMS showed that the oil from catalytic liquefaction gave out more low molecular weightcompounds in comparison to the un-catalytic liquefaction oil.Key words: Coal; liquefaction; solvent-flow; GCMS; Ni catalyst; oil conversion; molecular weight compounds;asphaltene; pre-asphaltene; tetralinWith the increase in world energy demand and thedepletion of petroleum crude oil, efforts have beenmade by researchers to seek alternative new sources ofenergy. Renewable energy such as solar and biomasshave a high potential to cater for energy; however, withthe extensive world coal reserves, proper attention needsto be considered to further upgrade and fully utilize thispriceless fuel. Hence, with this in mind, studies of coalliquefaction to produce an alternative liquid fuel, as oneof the upgrading coal processes, have been increasing inrecent years. Intense efforts have been made to liquefy coal,with the processes such as pyrolysis, solvent extraction andcatalytic hydrogenation using either batch or solvent flowreactor system have achieved some degree of success. Insome countries, coal is used as a consumption material togenerate steam for production of electrical power. Bothgasification and liquefaction of coal produce gaseous andliquid fuels that can be easily transported (e.g. by pipeline)and conveniently stored in tanks. In the transportation andindustrial sector, more than 80% of the energy consumed isprovided by fossil fuel energy such as coal, petroleum andnatural gas which are the main energy resources worldwide(Anon 2002).Solvent flow reactor system has been used by manyresearchers for its ability to investigate the coal liquefactionprocess rather at high temperatures. One important aspectin the solvent flow reactor system is the enabling of theremoval, quenching and characterization of extracts releasefrom the coal prior to the onset of the product degradationreactions (Begon et al. 2002). In addition, the ability tointroduce fresh solvent throughout the liquefaction processwill be beneficial in yielding high coal conversion. Giventhat the extracts will flow out to be collected, the solventflow reactor can be manipulated by installing additionalreactor to it. In this study, the second reactor filled withcatalyst was installed, in order to increase the oil yieldconversion. Depending on the coal rank and condition, thecoal liquefaction processes are routinely being carried outat temperatures near or above 400ºC at which the coal willbe actively decomposed and the process is often written as:Coal• + H• = (Pre-asphaltenes + asphaltenes + oils)+ H 2 O + gasThe role and the importance of catalyst in coalliquefaction are well known. The addition of active1 Fuel Combustion Research Laboratory, Faculty of Applied Sciences, Universiti Teknologi MARA, 02600 Arau, Perlis, Malaysia* Corresponding author (e-mail: azlanishak@perlis.uitm.edu.my)7