Pencairan hidroterma telah terbukti sebagai salah satu kaedah yang mampu menghasilkan bahan bakar bio daripada alga secara efektif. Kajian bagi kesan kehadiran mangkin ke atas pencairan hidrotherma telah dilaksanakan untuk meningkatkan kuantiti dan kualiti minyak bio yang terhasil. Kajian proses pencairan hidroterma telah dijalankan pada nisbah spirulina kepada air (10 g/100 ml) pada suhu 270 °C. Beberapa faktor (kesan tempoh tindakbalas, kesan jenis mangkin dan kesan dos mangkin) telah diuji bagi menghasilkan kuantiti produk yang tertingi dengan kualiti yang terbaik. Tempoh tindakbalas telah di ubah dari 0 hingga 40 min dan didapati kuantiti maksimum bagi penghasilan minyak bio adalah pada tempoh masa 20 min (39 %). Jenis mangkin yang berbeza seperti zeolit-HY, K₂CO₃ , Al₂O dan MgO telah diuji bagi penghasilan minyak bio dan kuantiti tertinggi telah dicapai oleh zeolit-HY (41 %) diikuti dengan K₂CO₃ , Al₂O₃ dan MgO dengan nilai sebanyak 38.6, 38.1, dan 23.8 %. Kehadiran mangkin zeolite-HY juga didapati mampu meningkatkan kandungan C dan H di sambil mengurangkan nilai N dan O berbanding dengan bahan mentah. Kesan dos mangkin (0.05 g hingga 0.5 g) turut dikaji dan didapati sebanyak 0.1 g mangkin sudah mencukupi untuk menghasilkan kuantiti produk yang tertinggi (49.2 %). Kandungan C dan H dalam produk kajian dengan kehadiran mangkin didapati lebih tinggi daripada kajian tanpa kehadiran mangkin manakala kandungan O, N dan S dalam kajian dengan kehadiran mangkin kurang daripada kajian tanpa mangkin. Mangkin Zeolit-HY berupaya menghasilkan produk yang berkualiti tinggi dengan kandungan C dan H yang tinggi manakala kandungan O yang rendah berbanding dengan mangkin lain. HHV bagi minyak bio daripada kajian tanpa mangkin (29 MJ/kg) didapati rendah berbanding kajian dengan 0.1 g zeolite-HY (35 MJ/kg). Komponen utama yang didapati dalam kajian dengan kehadiran mangkin dan tanpa mangkin dikategorikan kepada karbonil, asid, hidrokarbon, aromatic, alkohol, dan ketone. Secara keseluruhannya, zeolit-HY mampu digunakan semula sebanyak 4 kali dan hanya sedikit pengurangan dalam kuantiti produk minyak bio yang terhasil.
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Hydrothermal liquefaction process has been proven as a promising method to produce bio-oil from microalgae. For the rationale to improve the yield and quality of the bio-oil, the effect of catalytic and non-catalytic hydrothermal liquefaction of spirulina as a feedstock was investigated. The process was performed at a fixed spirulina to water content (10 g/100 ml) at 270 °C in a batch reactor. Various operating parameters (effect of reaction time, effect of catalyst type and effect of catalyst dosage) were investigated for the rationale to attain the highest yield accompanied by the presence of high quality of bio-oil. The effect of reaction time was varied from 0 to 40 min and the highest yield of bio-oil was obtained at 20 min (39 %). Various type of catalysts such as zeolite-HY, K₂CO₃ , Al₂O and MgO were tested on the production of bio-oil and the highest yield of bio-oil was obtained by zeolite HY (41 %) followed by K₂CO₃, Al₂O₃ and MgO with 38.6, 38.1, and 23.8 %, respectively. In fact, the presence of zeolite HY managed to improve the percentage of C and H content while decreasing the N and O values as compared to the feedstock. The effect of catalyst dosage (0.01 to 0.5 g) was then performed and only 0.1 g of catalyst was required to attain the highest yield of bio-oil (49.2 %). The C and H content of the bio-oil obtained from catalytic HTL were found to be higher than those of the blank experiment while the O, N, and S contents of the bio-oil from the catalytic HTL were also lower than those of the blank experiment. Zeolite-HY catalyst managed to produce bio-oil of higher quality as it contain the highest C and H content and lowest in O content among the tested catalysts. The HHV of bio-oil produced from a blank sample (29 MJ/kg) was relatively lower compared to the value of bio-oil produced in the presence of 0.1 g zeolite catalyst (35 MJ/kg). The main components present in bio-oil produced from catalytic and non-catalytic HTL were categorized into carbonyls, acids, hydrocarbons, aromatics, alcohol, and ketone. Overall, zeolite HY managed to be recycled for 4th time of repetitions and only slight reductions in the yield of bio-oil was observed.
Production of bio-oil via catalytic and non-catalytic hydrothermal liquefaction of spirulina / Teng Siong Lim