Activated Carbon Carbonization Acacia wood sawdust Base Heterogeneous Catalyst Base impregnation Biodiesel Boiler Ash Catalyst Based Activated Carbon Chemical Engineering Coconut Shell Coconut dregs Flour H-ZSM-5 HCl Concentration Heterogeneous Catalysts Impregnation KOH Silica Gel Transesterification Vacuum Freeze Drying acidity activity heterogeneous catalyst kimia modified mordenite shape selectivity