Pengaruh rasio Ni/Mo dan kandungan Nb2O5 terhadap karakter, aktivitas dan selektivitas katalis Ni-Mo/Nb2O5-Gamma-Al2O3 fraksi aspalten dari aspal Buton
SARIFUDIN, Kasimir, Dr. Wega Trisunaryanti, MS
2004 | Tesis | S2 Ilmu KimiaTelah dipelajari pengaruh rasio Ni/Mo dan kandungan Nb2O5 tehadap karakter, aktivitas dan selektivitas katalis Ni-Mo/Nb2O5-γ-Al2O3 dan modifikasinya untuk perengkahan fraksi aspalten dari aspal Buton. Pembuatan Nb2O5-γ-Al2O3 dilakukan dengan mencampurkan Nb2O5 dan γ-Al2O3 dengan asam oksalat 10% (b/b) dalam air, sampai terbentuk sedikit pasta, diikuti dengan pengeringan dan kalsinasi. Katalis Ni-Mo/γ-Al2O3, Mo-Ni/γ-Al2O3, Ni-Mo/Nb2O5- γ-Al2O3 dan Mo-Ni/Nb2O5γ-Al2O3 dipreparasi dengan metode impregnasi menggunakan Ni(NO3)2⋅6H2O dan (NH4)6Mo7O24⋅4H2O sebagai senyawa precursor, dilanjutkan dengan pengeringan, kalsinasi, oksidasi dan reduksi. Jumlah Nb2O5 dalam katalis divariasi 0%, 6% and 12% terhadap jumlah γ-Al2O3. Total Ni dan Mo yang diembankan sejumlah 10% (b/b) dari γ-Al2O3, rasio Ni/Mo divariasi 1/4 dan 4/1. Karakterisasi katalis meliputi keasaman ditentukan menggunakan metode gravimetri yaitu pengukuran adsorpsi uap piridin, luas permukaan spesifik, total volume pori dan rerata jejari pori diukur dengan menggunakan Surface Area Analyzer (NOVA–1000). Proses hidrorengkah dilakukan dalam reaktor sistem alir fixed bed, dengan kondisi operasi meliputi suhu reaksi, waktu reaksi, tekanan, laju alir gas dan rasio katalis/umpan, masing-masing adalah 400°C, 3,5 jam, 10 atm, 333,30 ml/menit dan 1/4. Aspalten sebagai umpan merupakan fraksi pentane insoluble-benzene soluble (PI-BS) dari aspal Buton. Produk hidrorengkah berupa H2S ditentukan dengan metode titrasi iodometri, fraksi gas dan kokas ditentukan secara gravimetri dan fraksi cair dianalisis dengan kromatografi gas (GC). Hasil yang diperoleh menunjukkan bahwa keasaman, luas permukaan spesifik, total volume pori, rerata jejari pori, aktivitas dan selektivitas katalis dipengaruhi oleh rasio Ni/Mo dan kandungan Nb2O5 dalam katalis. Secara umum katalis dengan rasio Ni/Mo = 4/1 menghasilkan H2S dan fraksi bensin lebih tinggi sedangkan fraksi minyak gas lebih rendah. Fraksi bensin dan konversi total tertinggi diperoleh dengan menggunakan katalis Ni4-Mo1/Nb2O5(6%)-γ-Al2O3. Katalis ini mempunyai karakter luas permukaan spesifik, rerata jejari pori, total volume pori dan keasaman, masing-masing adalah 96,05 m2/g, 90,9 x10-3 (cc/g), 18,93 Å dan 0,38 mmol/g. Distribusi hasil hidrorengkah fraksi aspalten menggunakan katalis ini adalah gas (C1-C4, CO2 dan H2) = 51,49%, H2S = 3,13%, bensin = 11,36%, minyak gas = 3,69%, kokas = 0,40%, residu = 29,92% dan konversi total = 69,68%.
Effect of Ni/Mo ratio and Nb2O5 content towards characters, activity and selectivity of Ni-Mo/Nb2O5-γ-Al2O3 catalyst and its modifications for hydrocracking process of asphaltene from Butonian asphalt has been investigated. The Nb2O5-γ- Al2O3 was prepared by blending Nb2O5 and γ-Al2O3 with 10% (w/w) of oxalic acid in water, until a thick paste was obtained, followed by drying and calcination. Ni-Mo/γ- Al2O3, Mo-Ni/γ-Al2O3, Ni-Mo/Nb2O5-γ-Al2O3 and Mo-Ni/Nb2O5γ-Al2O3 catalyst were prepared by impregnation method using Ni(NO3)2⋅6H2O and (NH4)6Mo7O24⋅4H2O as a precursor, followed by drying, calcination, oxidation and reduction. The Nb2O5 content was varied as followed: 0%, 6% and 12% based on the γ-Al2O3. Total supported Ni and Mo in the catalyst was 10 % (w/w) based on γ- Al2O3 and Ni/Mo ratio was 1/4 and 4/1. Catalyst acidity was determined using gravimetric method by adsorption of pyridine vapor and specific surface area, total pore volume and average pore radius were measured by Surface Area Analyzer (NOVA–1000). The hydrocracking process was carried out in a flow system fixed bed reactor, operation condition included temperature, reaction time, pressure, gas flow rate and catalyst/feed ratio were 400°C, 3.5 h, 10 atm, 333.30 ml/minute and 1/4, respectively. The asphaltene was a pentane insoluble-benzene soluble (PI-BS) fraction of Butonian asphalt. The hydrocracking products, i.e: H2S was determined by iodometric titration method, gas fraction and coke were determined by gravimetric method and liquid fraction was analyzed by gas chromatography (GC). The result showed that acidity, specific surface area, total pore volume, average pore radius, activity and selectivity were affected by Ni/Mo ratio and Nb2O5 content in catalyst. In general, the catalysts with Ni/Mo ratio of 4/1 produced higher H2S, gasoline fraction and low gas oil fraction. The Ni4-Mo1/Nb2O5(6%)-γ-Al2O3 catalyst produced highest gasoline fraction and total conversion. This catalyst has specific surface area, average pore radius, total pore volume and acidity of 96.05 m2/g, 90.9 x10-3 (cc/g), 18.93 Å and 0.38 mmol/g, respectively. Product distribution of hydrocracking of asphaltene using this catalyst were gas (C1-C4, CO2 and H2) = 51.49%, H2S = 3.13%, gasoline = 11.36%, gas oil = 3.69%, coke = 0.40%, residue = 29.92% and total conversion = 69.68%.
Kata Kunci : Rasio Ni/Mo, Nb2O5-γ-Al2O3, hidrorengkah, aspalten, aspal Buton, Ni/Mo ratio, Nb2O5-γ-Al2O3, hydrocracking, asphaltene, Butonian asphalt
