The use of 3D printing technology to create a heterogeneous catalyst for biodiesel production from high free fatty acid oils

Abstract

This thesis presents a comprehensive study on the development and optimization of biodiesel production from high free fatty acid (FFA) oils using advanced three dimensional (3D) printing technology coupled with heterogeneous catalytic system to create catalytic reactors. The research comprises three parts: (1) a three-step biodiesel production process from sludge palm oil (SPO), (2) a comparison of four types of 3D-printed mixing elements for biodiesel production from refined palm oil (RPO), and (3) the preparation, characterization, and application of 3D-printed calcium oxide (CaO) blended with acrylonitrile butadiene styrene (ABS) catalytic reactors for biodiesel production from pretreated sludge palm oil (PSPO). For the first part of this study, it focused on the conversion of high FFA SPO, a by-product from palm oil mill plants, into high-purity biodiesel through a three-step process. The high initial FFA level in SPO of 89.16 wt.% was unsuitable for direct transesterification. This is because the base catalysts could react with the FFA in oil to form soap, resulting in a lower biodiesel yield during the reaction. To address this, a double-step esterification process was employed to reduce the FFA content in SPO to below 1 wt.% using a cost-effective 3D-printed rotor-stator type hydrodynamic cavitation reactor (HCR). The results showed that the first-step esterification process required 60.8 vol.% methanol content, 7.2 vol.% sulfuric acid (H2SO4) content, 5.0 mm diameter of the hole, 6.1 mm depth of the hole, and 3000 rpm speed of the rotor. Consequently, the FFA content decreased to 36.69 wt.% in the actual experiment. Further a second-step esterification process was required to convert the remaining FFA content. In a subsequent experiment, final FFA content of 0.94 wt.% with PSPO yield of 115.6 vol.% were achieved in PSPO under 44.5 vol.% methanol content, 3.0 vol.% H2SO4 content, 4.6 mm diameter of the hole, 5.8 mm depth of the hole, and 3000 rpm speed of the rotor. Subsequently, the residual glycerides were converted to over 96.5 wt.% methyl ester (ME) purity using HCR and ultrasound. The second part investigated the role of 3D-printed static mixer reactor (SMR) in continuous biodiesel production from RPO. Four types of mixing elements, namely twisted plate static mixer (TPSM), cross semi-elliptical static mixer (CSSM), X-grid static mixer (XGSM), and corrugated plate static mixer (CPSM), were investigated to produce biodiesel. The CPSM type exhibited superior performance, achieving the highest ME purity of 99.77 wt.% with biodiesel yield of 98.3 vol.% under the optimal conditions of 30.9 vol.% methanol content, 13.3 g/L potassium hydroxide (KOH), and 3.4 m static mixer length. The third part of this research focused on 3D-printed CaO/ABS catalytic reactors, which were the primary focus of preparation and characterization of catalytic filament for use in the biodiesel production process. The catalytic filaments were created by blending 15 wt.% CaO with ABS plastic, showing the core technology of this thesis. This catalytic material demonstrates excellent mechanical, thermal, and catalytic properties, which is crucial for transesterification reaction of PSPO. Additionally, CaO/ABS catalytic mixing elements were fabricated using fused deposition modeling (FDM) 3D printing, which served as the key part of this thesis. These mixing elements significantly enhanced the transesterification reaction by improving blending and mass transfer between PSPO and methanol, while enhancing the reaction through the catalytic activity of CaO. According to the results, the CaO/ABS catalytic static mixer (CSM) reactor achieved an ME purity of 94.2 wt.% with biodiesel yield of 87.1 wt.% under the recommended conditions of 12:1 methanol to oil molar ratio and 8.5 h circulation time. The CSM coupled with ultrasonic tubular clamp (CSM/US) reactor reduced the circulation time to 2.25 h and increased the ME purity to 96.5 wt.% with biodiesel yield of 86.5 wt.%. Additionally, the reusability testing confirmed that the catalytic mixing elements could be reused for at least three cycles. Additionally, pulsed ultrasound operation reduced electricity consumption by 37.6%, demonstrating its potential for energy-efficient biodiesel production. Thus, the CaO/ABS catalytic reactor addressed the limitations of conventional CaO solid catalyst by improving mixing, enhancing mass transfer, reducing pressure drop, and minimizing filtration challenges.In conclusion, this thesis presents a comprehensive approach to biodiesel production by integrating advanced heterogeneous catalytic system with 3D printing technology to create the printed static mixer and printed HCR reactors. The findings contributed to the development of cost-effective, energy-efficient, and environmentally friendly biodiesel production technology. Moreover, this research addressed critical challenges in biodiesel production, including catalyst recovery, reusability, energy efficiency, and the utilization of high-FFA waste oils, providing a strong foundation for future industrial applications of 3D-printed catalytic reactors.

??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? (Heterogeneous catalyst) ????????????????????????????????????? (Catalytic reactor) ?????????????????????????????? ?????????? (1) ????????????????????????????????????????????????????????? (Sludge palm oil, SPO) (2) ????????????????????????????????????? (Mixing element) ??????????????????????????????????????????????????????????? (Refined palm oil, RPO) ??? (3) ??????????????? ????????????????????? ??????????????????????????????????????????????????????????? (Calcium Oxide, CaO) ?????????? ABS ????????????????????????????????????????????????????????????????????????????? (Pretreated Sludge Palm Oil, PSPO) ??????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????? 89.16 wt.% ?????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????? 1 wt.% ??????????????????????????????????????? (Hydrodynamic cavitation reactor, HCR) ????????????????????? ????????????????????????????????????????????????????????????????????????????? ?????????????? 60.8 vol.% ??????????????????? 7.2 vol.% ????????????????????????????????????? 5.0 mm ??????????????????????? 6.1 mm ??????????????????????????????? 3000 rpm ????????????????????????????????????????? 36.69 wt.% ????????????????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????? ????????????????????????????????????????? 0.94 wt.% ???????????????????????????? 44.5 vol.% ??????????????????? 3.0 vol.% ????????????????????????????????????? 4.6 mm ??????????????????????? 5.8 mm ??????????????????????????????? 3000 rpm ?????????????????? 115.6 vol.% ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 96.5 wt.% ??????????????????????????????????????????????????????????????????????????????????????????????????? ???????????????????????????????????????????????????????????????????? (Static mixer reactor, SMR) ???????????????????????????????????????????????????????????????????????????? ?????????????????????????? ?????? twisted plate static mixer (TPSM), cross semi-elliptical static mixer (CSSM), X-grid static mixer (XGSM), ??? corrugated plate static mixer (CPSM) ???????????????????????????????? ?????????????????????????????????????????? CPSM ????????????????????????????????????????????????????????????????????????????????? 99.81 wt.% ??????????????????????????????????? ?????????????? 30.9 vol.% ??????????????????????????? 13.3 g/L ????????????????????????????????? 3.4 m ?????????????????? 98.3 vol.% ???????????????????????????????????????????????????? ????????????????????? ??????????????????????????????????????????????????????????????? ????????????????????????????????? 15 wt.% ?????????????? ABS ??????????????????????????????????????????????????????????????????????????? ????????????????????????????????????? ???????????????????????????????? ???????????? ???????????????????????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????? (Catalytic static mixer, CSM) ??????????????????????????????????????? 94.2 wt.% ?????????????????????????????????????????????? 12:1 ???????????????????????? 8.5 h ?????????????????? 87.1 wt.% ?????????????????????????????????????????????????????????????????????????????????? (CSM/US) ?????????????????????????????????????????? 96.5 wt.% ?????????????????? 86.5 wt.% ???????????????????????????????????? 2.25 h ?????????????????????????????????????????? ??????????????????????????????????/????????????? (Pulsed mode) ????????????????????????????????????? 37.6% ????????????????????????????????????????????????????????????? ???????????? ???????????????? ??????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????? ?????????????? ????????????????????????? ????????????????????????? ???? ????????????????????????????????? ????????????? ???????????????????????????????????????????????????????????????? ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ? ???????