Synthesis ZrO 2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil

Research on synthesis and characterization of ZrO2-Montmorillonit and its application as catalyst in heavy fraction of crude oil (HFCO) conversion has been investigated. Synthesis of catalyst was done by pillarization of ZrO2 into silicate interlayer of montmorillonite structure. The success in synthesis is shown by XRD and BET surface area measurement in that basal spacing d001 was increase after pillarization. Activity test of material was showed that ZrO2 dispersion affected catalytic activity in liquid production and the activity was increased asn increasing temperature in the range of 473K-673K. Composition of liquid product indicated that ZrO2-Montmorillonit tend to produce kerosene related to metal oxide distribution in synthesis. © 2008 CREC UNDIP. All rights reserved. .


Introduction
Crude oil, a restricted and non renewable energy source, is the main source of energy and fuel in indonesia.In additional, Indonesian crude oil consist of heavy fraction in a high precentage ( about 60%) so an efficent conversion of crude oil into liquid fuel is so important.Catallytic reactions consist of cracking and hydrocracking became important to the refinery processing.In order to minimize energy consumed during the process, best characters of solid catalyst such as high surface area and thermal stability, high conversion and selectivity into gasoline product, are needed.Several investigation are focused on optimization in

Synthesis ZrO2-Montmorillonite and Application as Catalyst in
Catalytic Cracking of Heavy Fraction of Crude Oil Is Fatimah 1) *) , Karna Wijaya 2) , Khoirul Himmi Setyawan 3) 1) Chemistry Department, Islamic University of Indonesia, Yogyakarta, Kampus Terpadu UII, Jl.Kaliurang Km.14, Besi, Yogyakarta 55581 2) Chemistry Department, Gadjah Mada University, Sekip Utara, Yogyakarta 3) Center of Biomaterial Research, LIPI, Kompleks LIPI, Serpong catalyst synthesis, mainly in the form of metal and metal oxide dispersed onto the stable solid support.As well as synthetic silica alumina materials, natural montmorillonite, a kind of smectite class of clay, is a potential mineral to contribute as solid support for metal oxide catalyst.The lack of thermal stability of clays could be eliminated by pillarization process.This process cosist of two important steps : intercalation of silica sheet of smectite layer with polyoxocation of metal and calcination stable metal oxide.Research process to the polyoxocation to form a stable oxide.

Research on preparation and characterization of pillared clays has grown continously with the aim
Copyright © 2008, BCREC, ISSN 1978-2993 to improve physicochemical properties and catalytic activity in several important reaction.Several metal oxides have been reported for this purpose, such as Al, Zr, Ti, Cr, and mixed metal: such as Ga-La, Cr-Al in order to gain designed character of materials.Although the Al polyoxocation is by far the most studied pillaring agent in both scientific and patent literature, in the term of cracking catalyst, zirconium oxide pillared catalyst became important related to its high thermal stablity properties and Lewis acidity that play important role in the cracking mechanism ( Moreno et.al., 1999, Olezska, 2004).By far, pillarization of montmorillonite by ZrO2 reported by several author showed the potential application in such high temperature reaction.Zirconium oxide pillared clays exhibit a significantly high d (001) value to ~20Å and high surface areas (mostly 200-300 m 2 / g) depending on several preparation variables (Bartley and Burch, 1989, Kloprogge, 1999, Gil et.al, 2000).
In this investigation, synthesis, characterization and utilization of zirconium oxide pillared montmorillonite in heavy fraction of crude oil was conducted.Physicochemical properties of pillared montmorillonite synthesized were characterized by evaluate XRD pattern of materials (by X ray Diffraction (XRD)), BET surface area analyzer, Zr content (X-ray Fluorescence) and thermal stability (DTA-TGA).Catalytic activity of material in heavy fraction of crude oil was determined by the selectivity profile to produce kerosene, gasoline and gas oil fraction in cracking reaction

Techniques
Natural montmorillonite sample was taken from Boyolali, Central of Java and heavy fraction of oil derived by vacum fractional distillation to crude oil taken from Conoco Philip Co., Gresik, East Java.Preparation of zirconium pillared montmorillonite in this study is refer to previuos research (Fatimah and Wijaya, 2004) as modification to as reported by Bartley and Burch (1981), Wenyang et.al (1991) and Maes et.al.(1997).Preparation was started by preparation of Zr 4+ Keggin ion.This polyoxocation was obtained by refluxing ZrOCl2.8H2Oprecursor with ethylene glycol solution for 4 h.As produced, slow titration of a solution into montmorillonite suspension and stirred for 3 days.The following processes are neutralization (until Cl-free) and drying.Material resulted by this step was designated as ZrO2-M pre calc.Then sample was calcined at 400 o C for 3 h and designated as ZrO2-M.
Physicochemical characterisation of the samples included surface area analyzer-(nitrogen adsorption at 77 K) using NOVA1000 , X-ray diffraction (XRD-Shimadzu X6000), and Zr content determination by X-ray Fluorescence.Identification.X-ray powder diffraction patterns were obtained by using a Shimadzu X6000 diffractometer, at 40 kV and 30 mA, and employing Ni filtered Cu Ka radiation.

Activity Test
Catalytic performance of Zirconium oxide pillared montmorillonite was evaluated in cracking of heavy fraction of crude oil (HFCO).Reaction was carried out in a fixed bed stainless steel reactor with inner diamm. of 1.5 cm and 25 cm in length.
The pelletized catalyst (0,2 g, 200 mesh) was placed in catalyst holder within the reactor and mass ratio of catalyst to feed is 0.2.An ultra high purity of N2 gas was used as feed vapor carrier.Result of reaction was analyzed by gas chromatography -mass spectrometry(GC-MS Shimadzu QP-5000).

Results and Discussion
Physicochemical characters of raw montmorillonite used in this research are presented in Table 1.
In order to identify basal spacing d001 increase, XRD measurement was performed to raw montmorillonite, Zr-intercalated montmorillonite before calcination/pre calcined ( ZrO2-M pre calc) and ZrO2-montmorillonite(ZrO2-M).XRD patern of these materials is presented in Fig. 1 .
The patterns shows specifics reflection correspond to the montmorillonite mineral identitiy; d001 reflection at around 5-6 o and other reflection at around 20 o .The third reflection at around 23o   decomposition.BET surface area analysis data of the materials is presented in Table 2.

Bulletin of Chemical Reaction Engineering & Catalysis, 3(1-3), 2008, 10
The surface area of the pre calcined and calcined zirconium oxide pillared montmorillonite seems to be not related to the crystallinity of materials.It may caused by pore distribution of materials in that there is a modal pore produced as indication the metal oxide agregation in surface or called as house-of cards formation as reported in previuos publication.It can be detected from higher pore radius in ZrO2-M than do in raw montmorillonite.

Catalytic Activity
Catalytic activity of materials in HFCO cracking first evaluated by precetage of product distribution.Product distribution as fucntion of reaction temperature by using thermal condition, raw montmorillonite and ZrO2-M as catalyst is presented in Figure 3.
Effect of catalyst is shown by liquid production in catalytic cracking using both of raw montmorillonite and ZrO2-M catalyst.Its indicate that there is a cationic mechanism during reaction as alternate step to the radical mechanism in thermal reaaction.This assumption is also proven by high percentage of gas production in all temperature by thermal condition.Percentage of Liquid yield was increase as the use of raw montmorillonite and ZrO2-M catalyst respectively as indication that there was a positif effect of ZrO2 distribution in materials.Active site in surface tend to produce liquid product and decrease gas product as the change of mechanism involved.Temperature was also affected the liquid production.It could be concluded that ZrO2-M catalyst was play an important role in the cationic mechanism and activated by temperature.
Furthermore, from GC-MS analysis of the liquid products, selectivity of catalyst were evaluated.Selectivity to the special product are devided into kerosene, gasoline and gas oil product.Data in the histogram is presented in Figure 4.
Activity of the catalyst is required to determine the ability of the catalysts to convert a reactant into a desired product in a certain reaction.More intensive analysis to the liquid product resulted selectivity data that defined as persentage weight of specific fraction in the liquid.
Composition of liquid were obtained from peak area distribution in GC-MS analysis and expressed as peak area of selected fraction devided to total peak area of liquid product.According to Fessenden and Fessenden(1986), liquid petroleum distillates were grouped into gasoline (C5-C10), kerosene (C11-C12), gas oil (C13-C17), and heavy gas oil (C18-C25).
It can be seen from Figure 4 that selectivity of ZrO2-M is not significantly different with selectivity of raw montmorillonite, but from both of heavy fraction selectivity data, it concluded that at relative low temperature (473K), there is a high conversion of heay fraction into kerosene fraction.Gasoline was higher distributed in liquid product by using raw montmorillonite than do ZrO2-M catalyst in all varied temperature and was increased in elevated temperature.In the same catalyzed liquid production, kerosene distribution was not affected by temperature.In contrast, by using ZrO2-M catalyst, kerosene production was increased by increasing temperature.This data indicated that ZrO2-M catalyst tend to produce kerosene fraction in a high selectivity.This data was in agreement with as reported by Wenyang et.al (1991) in that lower gasoline distribution was produced in higher content of Zr in Zr-Al-pillared montmolrillonite.Pore size distribution is main factor controlling this mechanism.When the pillaring agent was added in excess, the amount of pillaring agent in the clay layers became denser, the pores became smaller, and the cracking activity decreased.The dense aggregate produce in a house of cards formation in this synthesis and reported before was important consideration to optimize physicochemical character of ZrO2montmorillonite in further research.

Conclusions
Pillarization of montmorillonite with zirconium oxide was produce active catalyst in HFCO cracking.Higher basal spacing d001 of montmorillonite resulted in synthesis was not linear with specific surface area indicate that there is a metal oxide aggregation as house of cards represented.Due to this character, although there is a positive effect of ZrO2 dispersion in montmorillonite structure to the liquid production, selectivity of catalyst to produce kerosene fraction was higher than to produce gasoline fraction.

Figure 3 .
Figure 3. Product distribution of HFCO cracking at varied temperature (a) thermal condition (b) using raw montmorillonite as catalyst (c) using ZrO2-M as catalyst

Table 1 .
Characterization Data of raw Montmorillonite correspond to the silica sheet in the structure.High intensity of d001 reflection indicate that there is high crystallinity and content of montmorillonite mineral in the sample, and furthermore, d001 value is equal to 14,47 Å.As silica sheet thikness is equal to 9.6Å, theoritic silicate interlayer space in raw montmorillonite is equal to 4.87Å.There is a shift of d001 reflection into lower angle correlate to

Table 2 .
BET surface area analysis data of raw montmorillonite, ZrO2-M pre calc and ZrO2-M