SINTESIS KATALIS Cu, Mn, Mg-Cu, DAN Mg-Mn TEREMBAN PADA KARBON AKTIF UNTUK KONVERSI 1-BUTANOL MENJADI 1,1-DIBUTOKSIBUTANA

YOESWONO, Prof. Dr. Triyono, S.U.

2017 | Disertasi | S3 Kimia

Telah dilakukan sintesis katalis Cu, Mn, Mg-Cu, dan Mg-Mn teremban pada karbon aktif untuk konversi 1-butanol menjadi 1,1-dibutoksibutana. Karbon aktif diekstraksi berturut-turut menggunakan aseton dan HCl 1 M, selanjutnya dilakukan pengembanan kering hingga diperoleh kadar tiap logam dalam karbon aktif sebesar 1% berat dan selanjutnya dikalsinasi dan direduksi. Katalis dikarakterisasi menggunakan X-Ray Diffraction (XRD), Thermogravimetry/ Differential Thermogravimetry (TG/DTG), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), adsorpsi isotermal N2, Fourier Transform Infra Red (FTIR), titrasi Boehm, adsorpsi piridina, dan Atomic Absorption Spectrophotometer (AAS). Sintesis 1,1-dibutoksibutana dilakukan dengan mengalirkan 1-butanol secara kontinu ke dalam reaktor kaca (i.d. = 1 cm dan p = 50 cm) tipe aliran ke bawah yang berisi katalis dalam lingkungan N2. Pengaruh temperatur, laju alir total, waktu reaksi, rasio laju alir 1-butanol/laju alir total, dan penambahan Mg terhadap pembentukan 1,1-dibutoksibutana dievaluasi. Produk reaksi dianalisis dengan Gas Chromatography (GC) dan Gas Chromatography-Mass Spectrometry (GC-MS) dan keberadaan 1,1-dibutoksibutana dikonfirmasi dengan FTIR dan Nuclear Magnetic Resonance (NMR), yaitu 1H, 13C, dan Heteronuclear Single Quantum Coherence (HSQC). Pengaruh penambahan 1,1-dibutoksibutana terhadap mutu minyak solar dikaji dengan uji mutu 5% dan 10% volume 1,1-dibutoksibutana dalam minyak solar. Karbon aktif hasil ekstraksi mengalami peningkatan luas permukaan dan peningkatan keasaman dibandingkan karbon aktif awal. Data XRD, TG/DTG, dan SEM-EDS mengindikasikan terbentuknya logam Cu dan Mn pada permukaan karbon aktif. Pengembanan logam menyebabkan penurunan luas permukaan karbon aktif dan penurunan tersebut semakin besar dengan penambahan Mg. Keberadaan gugus-gugus fungsional pada permukaan karbon aktif dimungkinkan memberikan kontribusi pembentukan 1,1-dibutoksibutana. Katalis Mn/karbon aktif memiliki aktivitas lebih tinggi dibandingkan katalis Cu/karbon aktif dan karbon aktif, tetapi aktivitasnya menurun lebih cepat dibandingkan katalis Cu/karbon aktif. Interaksi antara adsorbat dengan Mn yang lebih kuat dibandingkan dengan Cu dimungkinkan sebagai penyebab dan penambahan Mg meningkatkan kekuatan adsorpsi lebih lanjut. Rasio laju alir 1-butanol/laju alir total yang tinggi menurunkan pembentukan 1,1-dibutoksibutana akibat terhalangnya desorpsi butanal dari dalam pori oleh 1-butanol yang teradsorpsi di sekitar mulut pori. Rantai hidrokarbon yang xviii relatif pendek, posisi atom O yang relatif tersembunyi, dan adanya hidrogen yang terikat pada karbon tersier menjadikan penambahan 1,1-dibutoksibutana ke dalam minyak solar tidak membentuk ikatan spesifik sehingga menghasilkan volume molar berlebih bernilai positif pada seluruh rentang konsentrasi, membentuk campuran homogen dan stabil, meningkatkan angka cetana dan lubrisitas, menurunkan viskositas dan panas pembakaran per satuan berat.

Study on synthesis of Cu, Mn, Mg-Cu, and Mg-Mn catalysts impregnated on activated carbon for 1-butanol conversion to 1,1-dibutoxybutane has been done. The activated carbon was extracted sequentially by acetone and 1 M HCl solution, then metal salt of catalyst was dry impreganted on the activated carbon in such a way to give 1% wt. of metal catalyst to activated carbon and then calcined and reduced. The formed catalysts were characterized by X-Ray Diffraction (XRD), Thermographymetry/Differential Thermogravimetry (TG/DTG), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), N2 isothermal adsorption, Fourier Transform Infra Red (FTIR), Boehm titration, pyridine adsorption, and Atomic Absorption Spectrophotometer (AAS). The 1,1 dibutoxybutane was synthezised by continuously introduced of 1-butanol through down flow type of a quart tube reactor (i.d. = 1 cm and l = 50 cm) filled with catalyst under N2 atmosphere. Temperature, total flow rate, reaction time, 1-butanol to total flow rate ratio, and Mg addition effects on 1,1-dibutoxybutane formation were studied. Reaction product was analyzed by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS) and the existent of 1,1-dibutoxybutane was confirmed by FTIR and Nuclear Magnetic Resonance (NMR), i.e. 1H, 13C, and Heteronuclear Single Quantum Coherence (HSQC). 1,1-Dibutoxybutane addition effect on diesel fuel quality was studied by quality testing of 5% and 10% volume mixtures of 1,1-dibutoxybutane in diesel fuel. The surface area and acidity of extracted activated carbon was higher compared to that of unextracted one. XRD, TG/DTG, and SEM-EDS data indicated Cu and Mn metals were formed on activated carbon surface. The metal impregnation has decreased the surface area and more pronounced when Mg was added. The surface functional groups on the activated carbon may contribute on 1,1-dibutoxubutane formation. The Mn catalyst has highest activity compared to activated carbon and Cu catalyst but its activity decreased faster compared to that of Cu catalyst. It may due to stronger Mn-adsorbate interaction than activated carbon- and Cu-adsorbate interaction and Mg addition has further increased the interaction strength. The higher 1-butanol to total flow rate ratio has decreased 1,1-dibutoxybutane formation because of formed butanal desorption from pores was blocked by adsorbed 1-butanol around pores. 1,1-Dibutoxybutane has short branch chains, two oxygen atoms in hidden position, and a hydrogen bound at tertiary carbon made its addition into diesel fuel gave positive values of excess molar volume over all concentration ranges, formed homogeneous mixture and good phase stability, increased cetane number and lubricity, lowered viscosity and heat of combustion/weight unit.

Kata Kunci : Catalyst, 1-Butanol, 1,1-Dibutoxybutane