Transesterification of Rapeseed Oil for Synthesizing Biodiesel by K/KOH/γ‐Al₂O₃ as Heterogeneous Base Catalyst

Abstract

The heterogeneous base catalyst, c-Al 2 O 3 loaded with KOH and K (K/KOH/c-Al 2 O 3 ) was first prepared and used in the transesterification of rapeseed oil with methanol to produce biodiesel. The prepared catalyst was characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller method, infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that when c-Al 2 O 3 is loaded with KOH and K, the Al-O-K species is produced, resulting in an increase in the catalytic activity. The impacts of catalyst preparation conditions on the catalytic activities of K/KOH/c-Al 2 O 3 were investigated. The results demonstrate that the catalyst K/KOH/c-Al 2 O 3 has high catalytic activity when the added amounts of KOH and K are 20 and 7.5 wt% respectively. The transesterification of rapeseed oil to biodiesel with the prepared heterogeneous base catalyst was optimized. It was found that the yield of biodiesel can reach as high as 84.52% after 1 h reaction at 60°C, with a 9:1 molar ratio of methanol to oil, a catalyst amount of 4 wt%, and a stirring rate of 270 g.

Sodium phosphate as a solid catalyst for biodiesel preparation

“…Acceleration of the rotation speed could make the mixing more efficient and increase the reaction rate. The improvement of the reaction rate by increasing the rotation rate was also observed by other researchers when a different solid base was used (Ma et al 2008). …”

Advancements in Heterogeneous Catalysis for Biodiesel Synthesis

“…The loading of many kinds of alkaline salts on supports have been reported as a way to prepare basic catalysts, such as NaOH [2,[26][27][28][29], KOH [30,31], K 2 CO 3 [32], KI [33,34], KNO 3 [35,36], KF [37][38][39][40], and LiNO 3 [41,42]. The supports for these catalysts include Al 2 O 3 [33,39], Zeolite [43], ZnO [41] and SiO 2 [34].…”

Esterification Optimization of Crude African Palm Olein Using Response Surface Methodology and Heterogeneous Acid Catalysis

“…In addition, the average elemental composition of clay (Table 2) tested that the ratio Si/Al is about 2.62 characteristic to MT-KSF. The EDS analysis indicates that the MT-KSF presents high percentages of oxygen, silicon, aluminum, and sulfur in the clay, contributing to the formation of Al-O-Si, Al-O-H, and S-OH, Si-O-H chemical bonds that constitute the skeleton of the clays [28][29][30]. The presence of these chemical bonds was confirmed by infrared spectroscopy analysis.…”

“…These chemical bonds forming Lewis and Brönsted acid sites, the molar ratio of Si/Al relate the amount of acid sites present in the clay. Low values of this ratio (Si/Al) indicate that the MT-KSF has high catalytic activity [28][29][30][31][32].…”