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Wega Trisunaryanti

Chemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta

Author-ID : 3959591

Chemical Engineering, Chemistry & Bioengineering Chemistry

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MULTIPLE REGRESSION ANALYSIS OF THE INFLUENCE OF CATALYST CHARACTERS SUPPORTED ON γ-Al2O3 TOWARDS THEIR HYDROCRACKING CONVERSION OF ASPHALTENE Wega Trisunaryanti; Triyono Triyono; Mudasir Mudasir; Akhmad Syoufian
Indonesian Journal of Chemistry Vol 4, No 1 (2004)
Publisher : Universitas Gadjah Mada

Multiple regression study of the influence of catalyst's characters with γ-Al2O3 as a support, including acidity, specific area, average pore volume, average pore radius, Ni content, and Mo content the hydrocracking conversion of asphaltene has been conducted.A multivariable regression analysis method, including regression analysis and correlation analysis, was applied on this study. Using multivariable regression, the characters of catalyst was correlated together with the data of the asphaltene conversions. Furthermore, using this method, the characters of catalyst, which have the greatest influence on conversion, may be evaluated. The results showed that there was a high correlation between catalyst characters and hydrocracking conversion of asphalten (r = 0.983). It means that the conversion was 98.3% correlated with the catalyst characters. The value of the multivariable determination coefficient was 0.966, indicating that at least 96.6% variation on the conversions was determined by combination of catalyst characters on this research. From the parameter value of regression equation, it could also be known that average pore radius and specific surface area were the two characters that have the greatest influence on the hydrocracking conversion of asphalten.

STUDY ON THE RATE OF REDUCTION OF Cr(VI) TO Cr(III) BY HUMIC ACID USING CONTINUM MULTICOMPONENT MODEL Uripto Trisno Santoso; Herdiansyah Herdiansyah; Wega Trisunaryanti; Sri Juari Santosa
Indonesian Journal of Chemistry Vol 4, No 1 (2004)
Publisher : Universitas Gadjah Mada

The objective of this study is to develop a rate equation for reduction of Cr(VI) by humic acid (HA) using a continuum multicomponent model. HA was extracted from peat soil samples in Gambut Subdistrict, South Kalimantan. Parameters influencing the rate of reduction, i.e., medium acidity ([H+]), as well as initial humic acid concentrations ([HA]o) and initial Cr(VI) concentrations ([Cr(VI)]o) were critically evaluated. Experiments were performed in triplicate tests. Aliquots of stock solution containing 100 mg/L HA were equilibrated for 24 h at pH 1.5, 2.05, 3.2, 5.6, and 6.5 before being spiked with 0.02 mM of Cr(VI). [Cr(VI)] was determined by 1,5-diphenylcarbazide spectrometric method. A similar set of rate experiments was conducted at a fixed pH of 1.5 and an [Cr(VI)]o of 0.02 mM and with [HA]o of 25, 50, 75, 100, 150, 200, and 250 mg/L. A third set of batch experiment was performed at pH 1.5, an [HA]o of 100 mg/L, and [Cr(VI)]o 0.01, 0.02, 0.05, 0.10, and 0.20 mM. The results showed that the rate of reduction cannot be adequately modeled by either a simple first- or second- order rate equation. A continum multicomponent model adequately describes the effect of solution parameters on the rates of Cr(VI) reduction.

PREPARATION OF Ni-Mo/MORDENITE CATALYSTS UNDER THE VARIATION OF Mo/Ni RATIO AND THEIR CHARACTERIZATIONS FOR STEARIC ACID CONVERSION Wega Trisunaryanti; Triyono Triyono; Denty Fibirna A
Indonesian Journal of Chemistry Vol 3, No 2 (2003)
Publisher : Universitas Gadjah Mada

The preparation of Ni-Mo/Mordenite catalysts with variation of Mo/Ni ratio and their characterizations for conversion of stearic acid have been conducted. The catalysts were prepared by loading a small amount of nickel and/or molybdenum on H-Mordenite (H-Mor) with total metal content = 1 wt% based on the mordenite. The metals was supported on to the mordenite by impregnation method using nickel nitrate and/or ammonium heptamolybdate solution. The Mo/Ni ratio was varied as follows 0/1, 1/0, 1/1, 2/1, and 3/1 produced Ni/Mor, Mo/Mor, Ni1-Mo1/Mor, Ni1-Mo2/Mor and Ni1-Mo3/Mor catalyst respectively. The catalysts were then calcinated with nitrogen, oxidized with oxygen and reduced by hydrogen.The characterizations of catalyst were carried out by measuring Ni and Mo contents using atomic absorbtion spectroscopy (AAS), acidity by ammonia vapour adsorption, specific surface area and pore size distribution by nitrogen gas adsorption (NOVA-1000). The catalyst characters on conversion of stearic acid were performed in a flow reaction system at 4000C under hydrogen stream (10 mL/min).The AAS analyses showed that the metal impregnated on to the H-Mor sample were consistent to the initial metal concentrations. The loading of Ni and/or Mo enhanced the acidity, however decreased the specific surface area and total pore volume of the H-Mor sample. The higher the acidity the higher the conversion of stearic acid and the lower the coke formation. The other catalyst characters gave the variation effects toward the stearic acid conversion. The conversions of stearic acid were 34,52%, 43,33%, 65,10%, 80,10%, 86,42% and 95,72% produced by Ni1-Mo3/Mor, H-Mor, Mo/Mor, Ni/Mor, Ni1-Mo2/Mor and Ni1-Mo1/Mor catalyst, respectively.

OPTIMATION OF TIME AND CATALYST/FEED RATIO IN CATALYTIC CRACKING OF WASTE PLASTICS FRACTION TO GASOLINE FRACTION USING Cr/NATURAL ZEOLITE CATALYST Wega Trisunaryanti
Indonesian Journal of Chemistry Vol 2, No 1 (2002)
Publisher : Universitas Gadjah Mada

Optimation of time and catalyst/feed ratio in catalytic cracking of waste plastics fraction to gasoline fraction using Cr/Natural Zeolite catalyst has been studied.The natural zeolite was calcined by using nitrogen gas at 500 oC for 5 hours. The chromium supported on to the zeolite was prepared by ion exchange methode with Cr(NO3)3.9H2O solution with chromium/zeolite concentration of 1% (w/w). The zeolite samples were then calcined with nitrogen gas at 500 oC for 2 hours, oxidyzed with oxygen gas and reduced with hydrogen at 400 oC for 2 hours. The characterization of the zeolite catalyst by means of Si/Al ratio by UV-Vis spectroscopy, acidity with pyridine vapour adsorption and Na, Ca and Cr contents by atomic adsorption spectroscopy (AAS). The catalyst activity test was carried out in the cracking process of waste plastics fraction with boiling point range of 150 - 250 °C (consisted of C12 - C16 hydrocarbons) at 450 oC for 30 min, 60 min and 90 min, and catalyst/feed ratio 1/1, 1/2, 1/3, ¼ (w/w). The result of catalyst activity test showed that the maximum number conversion of gasoline fraction (C5-C11) is 53,27% with relatively low coke formation using 1/3 catalyst/feed ratio and the cracking time of 60 min.. This catalyst has Si/Al ratio = 1,21 (w/w) , acidity = 0,16 mmol/g and Na content = 0,81%, Ca content = 0,15% and Cr content 0,24%.

Co-Authors Akhmad Syoufian Denty Fibirna A Herdiansyah Herdiansyah Mudasir Mudasir Sri Juari Santosa Triyono Triyono Uripto Trisno Santoso

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