High operative heterogeneous catalyst in biodiesel production from waste cooking oil

Our work aims to produce a new catalyst that was a highly operative in the production of biodiesel from waste cooking oil WCO. A heterogeneous solid acid catalyst (RS-SO3H) was prepared by fast pyrolysis of rice straw, then it was followed by a sulfonation process. It was formed by using concentrated sulfuric acid. The Fourier transform infrared spectroscopy (FTIR) analysis confirmed that the chemical structure consists of sheets of amorphous carbon with hydroxyl and carbonyl (OH and COOH) groups as well as high density of SO3H. The surface area of RS–SO3H and the average pore size were characterized by scanning electron microscopy (SEM) and surface area analyzer. The results of Thermogravimetric analysis (TGA) showed that RS–SO3H has favorable thermal stability. Conventional energy sources were exhausted. So, we examined the catalyst activity on developing alternative energy resources, It became more imperative and environment friendly. WCO is attracting increased attention in the biodiesel production by transesterification process. The factors affecting the transesterification process include reaction time and temperature, catalyst concentration and methanol: oil molar ratio, were studied. The maximum mass yield of biodiesel extended to 90.37%. The content of fatty acid methyl ester (FAME) is around 97.71 wt%, conversion efficiency% of raw material reached 90.38 wt% and %free fatty acid (%FFA) conversion was 91.1% at optimum conditions: 10 wt% catalyst using methanol: oil molar ratio (20:1) at 70 °C for 6 h. The FAME content% was determined by gas chromatography (GC). The physicochemical properties of the biodiesel produced are close to the commercial diesel and the ASTM standards biodiesel D6751. The reusability of the used catalyst indicated that the catalyst was highly operative in production biodiesel. Where % conversion efficiency of raw oil under optimized conditions decreased from 90.37 to 88.56% after 8 cycles. The %FFA conversion was constant around 91.1% until 7 runs then it decreased. Keywords: Biodiesel, Biodiesel characterization, Catalytic activity, Catalyst stability, Sulfonated solid acid catalyst, Waste cooking oil