THE EFFECT OF TEMPERATURE ON THE PERFORMANCE OF ACTIVATED CARBON OVER CATALYTIC CRACKING OF CRUDE PALM OIL

This research was carried out to investigate the effect of temperature in carbon production on its performance in the catalystic cracking of CPO to fuel.  The carbon was produced using palm shell at 2 different temperatures (450 and 550oC).  The cracking of CPO was carried out with and without the active carbon catalyst.  The result showed that the use of catalyst increase the conversion of both gas and liquid conversion.  The use of higher temperature in the production of active carbon catalyst increased the performance of the catalyst, in particular, for the liquid conversion. Keywords :Activated carbon, catalyst, catalytic cracking, crude palm oil


INTRODUCTION
Crude oil of fossil fuel balance in Indonesia shows a declining of crude oil production for about 4% per year, and in contrast a fuel consumption is incresing in average 4.7 % per year.If this situation still continue, it will change Indonesia status from crude oil exporter country to crude oil importer country in 2035 (Yudiartono et al., 2018).These facts had encouraged many scientists in Indonesia to search for the ways for efficient energy consumption along with the search for the new sources for fossil fuels and the researches for alternative renewable energy resources (Devita et al., 2017, Nazarudin et al., 2017) For developing a renewable energy, Indonesian government released Presidential Decree No. 2 of 2006 about Nasional Energy Policy describing the principles of energy diversification, Furthermore, the Presidential Decree No.2 of 2015 about National Medium Term Development Plan (RPJMN) stated the strategic poilicies of science and technology development including strategy of renewable energy.This policy emphasizes the use of alternatives energy such as plant-based fuels which is highly potential in Indonesia.(Devita et al., 2017, Nazarudin et al., 2017).Indonesia is the largest producer of crude palm oil in the world.The production of CPO in Indonesia was expected to reach at 40.5 million tons in 2018/2019, that grows approximately five percent from 2017/2018.Therefore, crude palm oil is one of some potential sources for plant based fuels which can be developed in Indonesia (Elst, 2018, McDonald and Rahmanulloh, 2018, Rafiie, 2018).
The high amount of CPO production in Indonesia has caused the high amount of waste produced in the factory.According to previous research, generally the solid waste produced from palm oil mill is empty bunch (24-35%).The utility of this waste has not optimally done.Nowadays, about 70% of solid waste is utilised by burning them to produce heat for boiler.This utilisation has produced charcoal and ash which are abundant.It is not like the ash which has been used for organic fertilizer, the carbon has not been utilised (Nazarudin et al., 2017).
The solid waste can be converted to activated carbon by combination of chemical and physical (calcination) treatment that can improve the physical and chemical properties of the material.A activated carbon in the form of granuluar and powder has a large pores which are a good for absorbency, catalyst, and catalyst support (Luangkiattikhun, 2007, Nazarudin et al., 2017, Rugayah et al., 2014).Metal-embedded catalyst such as Cr-Carbon and Ni-Carbon has many advantages where the active metals were better dispersed compare to those unembedded due to the increase in surface area of active site in metal catalyst (Nazarudin et al., 2017).However, the process to embed the metal into the catalyst requires some spaces in term of catalyst pores (Wan andHameed, 2011, Thushari andBabel, 2018).This current research was undergone to investigate the use of temperature in the activation of carbon as a process that can be used to increase the surface area of catalyst pores and in turn affects its performance in catalytic cracking of CPO to gasoline.

The Production of Carbon and Activation of Carbon Catalyst
The production of carbon was done by burning palm shells in the batch reactor at 450 and 550 o C without enough amount of oxygen.The activation of carbon was carried out chemically by using NaOH.Some amount of carbon was mixed using NaOH pellet and distilled water with ratio carbon:distilled water:NaOH was 1:3:1.This mixtures was stirred continously for 2 hours at 40 o C. The carbon was filtrated and washed.The carbon was then redissolved in CH3COOH 25% for 30 minutes and refiltrated.This procedures was repeated until the acid solution turned netral (pH=7).The carbon was dried in the dryer at 105 o C for 4 hours.

Characterization of Catalyst
The characterization was done by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM).

The Thermal and Catalytic Cracking
There were 2 cracking process done in the current research: thermal cracking and catalytic cracking.
Thermal cracking was carried out as comparison to those with catalysts.Similar process were done for both cracking process except for the use of active carbon in the vertical furnace at catalytic cracking process.The cracking was carried out by using ratio of catalyst to crude palm oil (CPO) 1: 10.Length of cracking was 1 hour with cracking reactor temperature was 723 K and horizontal furnace (gasification reactor) at 673 K.
CPO sample was injected to heated horizontal reactor.CPO flowed to vertical furnace and underwent heating to produce liquid yield which further being collected and weighed.Total solid residu was also weighed which consist of catalyst residu and cocass.

Gravimetric Analysis
Gravimetric analysis was carried out for cracking products: gases, liquid, cocass, and CPO residu.This analysis was done to calculate conversion for each cracking product (gasoline, diesel) and conversion ratio (gas + liquid)/cocass which was symbolised as H/K (Nazarudin, 2000).a. % cracking product

Gas Chromatography-Mass Spectroscopy (GC-MS)
Liquid produced during cracking was analysed using GC-MS to obtain type of hydrocarbon produced (qualitative) and the number of hydrocarbon in the liquid (quantitative).The operation condition for GC-MS can be seen at Table 1.

Active Carbon Catalyst
The use of different temperature in the production of active carbon catalyst has affected the crystallinity of catalyst produced.As shown in Fig 1 below, result from XRD showed the active carbon catalyst produced using 450 o C has less crystallinity compare to active carbon catalyst produced using 550 o C. The increase in the crystallinity of active carbon was as expected since it exhibits similar form of crystal catalyst.The uniformity of crystal catalyst can be used to predict the product of catalytic process more easily.
SEM images (Fig 2) confirmed that the use of higher temperature in the production of active carbon catalyst has removes the impurities present in the carbon.The result showed that the use of higher temperature (550 o C) gives better sites for metal to be embedded in the active carbon to increase its performance in the catalytic cracking.

Catalytic Cracking
The result of cracking of CPO is shown in Table 2.This result showed that the use of active carbon as catalyst increased both gas and liquid conversion.This result also showed that the use of active carbon catalyst has better performance in liquid conversion if it is produced at higher temperature (550 o C).At lower temperature (450 o C), active carbon catalyst produced less liquid and more gas.
As shown in Fig 2 and Fig 3, the chromatogram for liquid produced by both catalyst are similar, however, the compound present in the liquid as shown in Table 3 and Table 4 are actually different.

CONCLUSION
Solid waste from palm oil mill such as palm shell can be used to produce active carbon catalyst.Active carbon catalyst increased the conversion of both gas and liquid conversion in the catalytic cracking of CPO compare to thermal cracking.The use of higher temperature in the production of active carbon catalyst increased liquid conversion in the catalytic cracking of CPO

Fig 1 .
Fig 1. XRD pattern of active carbon catalyst produced using 2 different temperatures: 450 o C (below) and 550 o C (top)

Table 2 . The product of thermal and catalytic cracking of CPO at 500 o C
Fig 3. Chromatogram GC for liquid produced by catalytic cracking of CPO using active carbon catalyst produced at 450 o C , cracking temperatur 500 o C Fig 4. Chromatogram GC for liquid produced by catalytic cracking of CPO using active carbon catalyst produced at 550 o C , cracking temperatur 500 o C

Table 3 .
The compound in the liquid product of cracking using active carbon catalyst produced at 450 o C