Development of a small production platform for citronellal processing
- Authors: Mafu, Lubabalo Rowan , Zeelie, Ben
- Date: 2016
- Subjects: Organic compounds -- Synthesis , Plasticizers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8488 , vital:26370
- Description: The aim of the project was to develop a small production platform for citronellal processing. The objective of the study was to develop a single continuous flow reactor system for the synthesis of novel derivatives of citronellal and isopulegol. The first step was to develop a continuous flow reactor system for the isopulegol synthesis. The stainless steel tubular fixed-bed reactor equipped with a reaction column (I.D: 9.53 mm and length: 120 mm) was used for the study. The reactor column was packed with H-ZMS-5 zeolite extrusion catalyst. The solvent-free cyclisation reaction of citronellal was investigated and at optimum conditions, 100% of citronellal conversion and almost 100% selectivity towards isopulegol was achieved. A good catalytic performance was observed from the H-ZSM-5 catalyst and proved to be stable for a prolonged reaction time. The second reaction step was to develop a continuous flow reactor system for the synthesis of isopulegyl-ether derivatives. A UniQsis FlowSyn reactor system equipped with a stainless steel reactor column was used for the study. The reactor column was packed with amberlyst-15 dry catalyst. Wherein, n-propanol was employed as a model etherifying agent and as a reaction solvent. At optimum reaction condition, only 30% selectivity of isopulegyl propoxy-ether was achieved. The reaction was found to depend highly on temperature and residence time. The increase of these parameters was found to increase the side reactions and reduced the selectivity of the desired product. Other heterogeneous catalysts such as H-beta zeolite, aluminium pillared clay, Aluminium oxide and H-ZSM-5 were also evaluated in the reaction. Among these catalysts, a catalytic activity was observed with H-beta zeolite (19%) and aluminium pillared clay (5%). Based on these results, none of the evaluated catalysts provided the desired selectivity (greater than 70%) towards the isopulegyl propoxy-ether, therefore the process was not investigated further. In light of this, the isopulegol etherification synthetic route was terminated. Consequently, another analogue of citronellal was used as an alternative intermediate in place of isopulegol, namely para-menthane-3,8-diol (PMD). The initial studies for the synthesis of the novel PMD di-esters from isopulegol were performed in the batch-scale reactor. In a solvent-free reaction, acetic anhydride was initially used as a model acetylating agent. The reaction was performed using polymer-bound scandium triflate (PS-Sc(OTf)3) catalyst. The effect of reaction parameters such as temperature, molar ratio, and reaction time were studied towards the PMD conversion and di-esters selectivity. At optimum reaction conditions, PMD conversion of 70% and di-acetate selectivity of 67% were observed. The reaction was found to follow the zeroth-order kinetics with respect to PMD conversion and obeyed the Arrhenius equation. Other types of di-ester derivatives were synthesized from PMD by varying the carbon chain length of the acetylating agent. The prepared compounds were separated from the product mixtures by vacuum distillation, purified on a column chromatography and characterised by FT-IR, GC-MS, and 1H-NMR, 13C-NMR. The developed methodology was optimised in flow by using an ArrheniumOne microwave-assisted continuous-flow fixed-bed reactor system. A detailed experimental design was used to carry-out the reactions. The reaction parameters such as temperature and flow-rate were studied towards the PMD conversion and di-ester selectivity. From the experimental design analysis, the di-ester selectivity was found to depend highly on the residence time (flow-rate) and significantly on temperature. The PMD conversion and di-ester selectivity were found to increase with decrease in the flow-rate. The conversion and selectivity achieved in the continuous flow process were significantly higher than the achieved in the batch-scale process with respect to the residence time.
- Full Text:
- Date Issued: 2016
Benefication of glycerol from algae and vegetable oil
- Authors: Mafu, Lubabalo Rowan
- Date: 2011
- Subjects: Glycerin -- Biotechnology , Biodiesel fuels , Renewable natural resources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10409 , http://hdl.handle.net/10948/d1011503 , Glycerin -- Biotechnology , Biodiesel fuels , Renewable natural resources
- Description: This research has been directed at furthering the utilization of crude glycerol oversupply formed as a by-product from the biodiesel manufacturing process. Phosphorylation of hydroxyl groups is a synthetic route that was investigated for the conversion of glycerol into a glycerol-phosphate (GPE) ester mixture. The process investigated for the synthesis of a GPE product was based on phosphorylation reaction procedures that were previously reported in the literature. The reaction to convert glycerol into a GPE mixture has been thoroughly investigated and the hydrogen chloride gas formed as a reaction by-product has been optimized. The chemical properties of GPE have been studied and discussed together with a mass balance of the overall glycerol phosphorylation process. The phosphate groups contained in polyhydric phosphate molecules have a potential chelating effect on cations. There are several cations that may be chelated by the phosphate ester group of polyhydric phosphate molecules. These cations include ammonium (NH4+), Potassium (K+), Calcium (Ca2+) etc, which are essential as nutrients in plant fertilizer formulations. This research has investigated the use of a GPE synthesized from glycerol in the laboratory and the use thereof as a phosphorus containing base in the formulation and evaluation of Nitrogen, Phosphorus and Potassium (NPK) containing fertilizer solution, Ammonium-Potassium-Glycerol-Phosphate (APGP) fertilizer solution. The APGP fertilizer solution has further been evaluated by growing two week old tomato seedlings under controlled conditions. The performance of the APGP fertiliser solution has been evaluated using design of experiments by comparison with traditionally used liquidAmmonium-Potassium-Phosphate inorganic fertilizer. This fertilizer solution has been prepared in similar manner as APGP formulation with the difference between them being the source of phosphorus. The results have been evaluated using statistic analysis where a significant difference between the evaluated fertilizer formulations was found. The comparative study of these formulations was monitored by the observed plant weights. A blank treatment was used as a control to determine if a significant difference among these formulations was observed. Anova single factor and t-Test methods (Two-Samples assumed of equal variances) are statistical models that were applied to interpret the observed experimental data with respect to wet and dry weighed masses of tomato seedlings. These methods indicated a confirmed conclusion that there was a significant difference between APPO4 solution and APGP solution. The observed data have shown that the APPO4 solution provided significantly better fertigation performance than APGP solution. Consequently, further investigation has been conducted to determine the cause of the poorer performance of the APGP solution. The further study of the APGP fertilizer solution included nutrient stability testing, biological analysis and other observed physical changes of the APGP solution over time. Biological results have revealed the presence of a Fusarium fungus species that has grown and is suspended in APGP fertilizer solution. This microbe species has been observed to play a vital role in consuming fertilizer nutrients. In addition, the observed abnormal plant growth and nutrient decomposition of the APGP formulation has been proposed to be mostly a result of the pathogenicity of the fusarium fungi species that was suspended in the APGP solution. Further work has been proposed in which the effect of such biological contamination is eliminated through adequate sterilization procedures and the APGP formulation re-evaluated.
- Full Text:
- Date Issued: 2011