SYNTHESIS AND CHARACTERIZATION OF SILICA-SUPPORTED NiMo CATALYST USING NaHCO3 AS TEMPLATE FOR HYDROCRACKING OF WASTE COOKING OIL INTO BIOFUEL

ASMA' NADIA, Prof. Dr.rer.nat Karna Wijaya, M.Eng; Prof. Dr. Iip Izul Falah

2021 | Tesis | MAGISTER KIMIA

Sintesis, karaktersasi, dan aplikasi katalis NiMo/hierarki silika untuk konversi minyak goreng bekas menjadi biofuel telah dilakukan. Tujuan dari penelitian ini adalah untuk mempelajari pengaruh variasi mol TEOS:NaHCO3 terhadap sifat kesamaan hierarki silika, mempelajari pengaruh konsentrasi logam Ni dan Mo terhadap sifat fisik dan kimia katalis, serta membandingkan aktivitas, selektivitas katalis SiO2, HS3, NiMo/HS3, serta stabilitas katalitik NiMo/HS3 pada reaksi hidrorengkah minyak goreng bekas menjadi biofuel. Sintesis hierarki silika dilakukan dengan variasi mol TEOS:NaHCO3 pada 1:0,1; 1:0,2; dan 1:0,3. Hierarki silika dengan keasaman tertinggi digunakan sebagai pengemban dalam proses impregnasi logam Ni dan Mo. Impregnasi logam aktif dan promotor dilakukan dengan metode impregnasi basah secara simultan. Sampel katalis dikarakterisasi dengan FTIR, XRD, SEM-EDS, TEM, SAA, dan TGA/DTG, sedangkan fraksi cair yang diperoleh dari reaksi hidrorengkah dianalisis menggunakan GC-MS. Kondisi optimum proses sintesis hierarki silika diperoleh dengan menggunakan perbandingan rasio mol TEOS:NaHCO3 sebesar 1:0,3 dengan jumlah situs asam total sebesar 8,93 mmol/g. Penambahan NaHCO3 dalam sintesis silika dapat membentuk mikro dan mesopori yang seragam. Keberadaan logam NiMo pada hierarksi silika memberikan pengaruh pada peningkatan luas permukaan dan total nilai keasaman total. Luas permukaan katalis dan nilai keasaman total tertinggi dihasilkan oleh katalis Ni2Mo2/HS3 yaitu masing-masing sebesar 641,84 m2/g dan 12,05 mmol/g. Temperatur optimum dan rasio katalis/umpan pada reaksi hidrorengkah masing-masing dihasilkan pada 475 ºC dan 1% b/b. Produk cair paling tinggi dihasilkan oleh katalis Ni2Mo2/HS3 sebanyak 68,57% yang terdiri dari fraksi bensin dan diesel masing-masing sebesar 18,64% dan 42,88% b/b. Uji stabilitas katalis Ni2Mo2/HS3 sebanyak 3 kali menunjukkan katalis Ni2Mo2/HS3 memiliki kemampuan self-regeneration.

Synthesis, characterization, and catalytic activity test of NiMo/hierarchical silica to convert waste cooking oil into biofuel by hydrocracking have been investigated. The aims of this research were to study the effect of various mole ratio of TEOS and NaHCO3 on the acidity of hierarchical catalyst, to study the effect of NiMo metal concentration on the physical and chemical properties of catalyst, and to compare the catalytic activity and selectivity of SiO2, HS3, and NiMo/HS3, and catalytic stability of NiMo/HS3 in the hydrocracking reaction of waste cooking oil into biofuel. Hierarchical silica was prepared with various ratios of TEOS:NaHCO3 of 1:0.1, 1:0.2, and 1:0.3. The highest acidity of hierarchical silica was applied as support in the impregnation process of Ni and Mo metal. The impregnation of active and promoting metal on support catalyst was done simultaneously via wet impregnation method. The impregnation of active and promoting metal on support catalyst was done simultaneously. The obtained catalysts were characterized by FTIR, XRD, SEM-EDS, TEM, SAA, and TGA/DTG, while the obtained liquid products from hydrocracking process were analyzed by using GC-MS. The optimum condition of hierarchical silica preparation process was achieved at mole ratio TEOS:NaHCO3 of 1:0.3 with the total amount of acid sites of 8.93 mmol/g. The addition of NaHCO3 in silica synthesis could produce uniform micropores and mesopores. The presence of NiMo on hierarchical silica could increase the surface area and total acidity of catalyst. The highest surface area and acidity value were obtained by Ni2Mo2/HS3 of 641.84 m2/g and 12.05 mmol/g, respectively. The highest liquid product was obtained by Ni2Mo2/HS3 of 68.57 wt% consist of gasoline and diesel fraction of 18.64 and 42.88 wt%. The stability test over 3 cycles showed that Ni2Mo2/HS3 has self-regeneration ability during the examination.

Kata Kunci : monodisperse hierarchical silica, NaHCO3, bimetal, hydrocracking, self-regeneration.