Baroroh, Vicario (2026) Konversi Berkelanjutan Aspal Buton Melalui Pirolisis: Residu Padat Termodifikasi Logam Sebagai Katalis Deoksigenasi Dan Adsorben Fosfat. Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Aspal Buton (RA) merupakan sumber hidrokarbon alam yang melimpah di Indonesia. RA mengandung kalsit (CaCO₃) dan senyawa hidrokarbon mirip minyak bumi seperti aspalten dan malten. Pirolisis langsung RA menunjukkan bahwa kalsit berperan sebagai katalis in situ alami yang efektif dalam mentransformasi cincin aromatik dari aspalten menjadi hidrokarbon dengan jumlah karbon dalam rentang bahan bakar diesel. Proses pirolisis pada suhu 400 °C selama 180 menit menghasilkan selektivitas minyak pirolisis aspal (APO) sebesar 74%, jauh lebih tinggi dibandingkan pirolisis RA terdekalsifikasi (23,71%) maupun RA terdekalsifikasi dengan penambahan CaCO₃ murni (35,04%). Produk cair hasil pirolisis didominasi oleh fraksi diesel (70,30%) dengan angka setana 69 yang menunjukkan kualitas bahan bakar yang baik. Interaksi kuat antara kalsit dan aspalten berperan penting dalam meningkatkan efisiensi perpindahan panas serta mendorong proses hidro-dearomatisasi dan perengkahan selektif menuju hidrokarbon rentang diesel. Selain menghasilkan bahan bakar cair, pirolisis langsung RA juga menghasilkan residu padat kaya CaCO₃ (CRA) yang hingga kini belum banyak dieksplorasi. Pada penelitian ini, CRA dimanfaatkan sebagai penyangga katalis melalui impregnasi logam Fe, Ni, dan Zn (Fe/CRA, Ni/CRA, dan Zn/CRA) untuk proses deoksigenasi guna meningkatkan kualitas APO yang masih mengandung senyawa oksigenat. Analisis GC–MS menunjukkan bahwa APO awal mengandung fraksi berat (C18 ke atas). Setelah proses deoksigenasi menggunakan katalis Ni/CRA, fraksi hidrokarbon C11–C18 meningkat signifikan menjadi 77,40%, disertai rendemen cair tertinggi (69,11%) dan pembentukan kokas terendah (1,42%), yang menandakan kinerja katalitik paling optimal. Selain sebagai katalis, CRA juga berpotensi sebagai adsorben fosfat. Kalsinasi CRA pada suhu 600–900 °C mengonversi CaCO₃ menjadi Ca(OH)2 aktif. CRA yang dikalsinasi pada suhu 800 °C menunjukkan kapasitas adsorpsi fosfat mencapai 769 mg/g. Proses adsorpsi berlangsung melalui mekanisme kemisorpsi dan adsorpsi heterogen, sebagaimana ditunjukkan oleh kesesuaian model isoterm Freundlich dan kinetika orde dua semu.
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Buton rock asphalt (RA) is an abundant natural hydrocarbon resource in Indonesia, composed of a mixture of calcite (CaCO₃) with petroleum-like materials. Direct pyrolysis of RA demonstrated that calcite acts as an effective natural in situ catalyst in transforming aromatic rings from asphaltenes into diesel-range hydrocarbons. The pyrolysis process at 400 °C for 180 minutes resulted in a selectivity of asphalt pyrolysis oil (APO) of 74%, much higher than the pyrolysis of decalcified RA (23.71%) and decalcified RA with the addition of pure CaCO₃ (35.04%). The pyrolysis liquid product was dominated by diesel fractions (70.30%) with a cetane number of 69, which indicates superior fuel quality. The strong interaction between calcite and asphaltenes plays a significant role in increasing heat transfer efficiency and promoting the hydro-dearomatization process and selective cracking towards diesel-range hydrocarbons. In addition to producing liquid fuel, direct pyrolysis of RA also produces a CaCO₃-rich solid residue (CRA), which has not been widely explored to date. CRA, in this study, is utilized as a catalyst support through the impregnation of Fe, Ni, and Zn metals (Fe/CRA, Ni/CRA, and Zn/CRA) for the deoxygenation process to improve the quality of APO, which still contains oxygenated compounds. GC–MS analysis showed that the initial APO contained a heavy fraction (C18 and above). After the deoxygenation process using the Ni/CRA catalyst, the C11–C18 hydrocarbon fraction increased significantly to 77.40%, accompanied by the highest liquid yield (69.11%) and the lowest coke formation (1.42%), indicating the most optimal catalytic performance. In addition to being a catalyst, CRA also has the potential to be a phosphate adsorbent. Calcination of CRA at 600–900 °C converts CaCO₃ into active Ca(OH)2. CRA calcined at 800 °C showed a maximum phosphate adsorption capacity of 769 mg/g. The adsorption process proceeded through chemisorption and heterogeneous adsorption mechanisms, as indicated by the good fit of the Freundlich isotherm and pseudo-second-order kinetics models.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | Aspal Buton (RA), pirolisis, kalsit, katalis, bahan bakar, adsorpsi, fosfat. |
| Subjects: | Q Science > QD Chemistry > QD117 Absorption Q Science > QD Chemistry > QD281 Pyrolysis Q Science > QD Chemistry > QD501 Catalysis. Catalysts. |
| Divisions: | Faculty of Science and Data Analytics (SCIENTICS) > Chemistry > 47001-(S3) PhD Thesis |
| Depositing User: | Vicario Baroroh |
| Date Deposited: | 04 Aug 2026 04:36 |
| Last Modified: | 04 Aug 2026 04:36 |
| URI: | http://repository.its.ac.id/id/eprint/140431 |
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