Effect of zeolite on the catalytic cracking of tar yields mahogany wood pyrolysis

Widya Wijayanti,Sasongko Nur,M Musyaroh

doi:10.5937/jaes0-29995

Abstract

In this study, the effects of zeolite were observed to investigate the formation of a pyrolysis product, which is tar yield. Tar yields receive the most attention because of their potential as a bio-oil and chemical feedstocks. For this reason, efforts to increase tar yield were made, one of which was by adding zeolite to the pyrolysis process. The role of zeolite here was a pyrolysis catalyst. This is a study that uses mahogany wood as the feedstock for a real, pilot plant pyrolysis reactor. Moreover, 0-50% of the feedstock's mass worth of zeolite was also introduced during the pyrolytic process. The temperatures set in this pyrolysis were 250 °C, 500 °C, and 800 °C. The test results were measured in terms of the tar yield's volume and mass. The volume of tar yields produced increased as the temperature increased due to more biomass decomposed. Then, the chemical composition of tar yield was tested using a Gas Chromatograph Mass Spectrometry (GC-MS) to measure the percentage of its chemical constituent compounds. Then, the formation mechanism of tar compounds from pyrolysis was described by using HyperChem simulation. The results showed that an increase in zeolite catalyst percentage would generate more volume of tar yields. It was due to the breaking of biomass hydrocarbon chains, increasing the production of tar yields. Zeolite also affected the formation of hydrocarbon chains in tar yields where the chains became shorter as the percentage of zeolite catalyst rose. The mechanism of increasing tar product was due to the role of zeolite as a catalyst in the catalytic cracking process which is almost similar to acid-base reactions of Brønsted-Lowry and Lewis. This reaction took place when the pyrolysis yields moved through the pores of zeolite, breaking the long hydrocarbon chains into shorter ones which were dominated by alkenes, aromatic, and acidic compounds formation. In addition, acidic compounds represented by acetic acid function as a flammable matter possess the potential of becoming oil-fuel.

Highlights

Pyrolysis is a method for converting biomass into fuel, whether as a solid, gas, or liquid fuel
It was found that the effect of thermal cracking and catalytic cracking was indicated by the relationship between pyrolysis temperature and tar volume yield produced by the pyrolysis of mahogany wood at temperatures of 250 °C, 500 °C, and 800 °C
When the pyrolysis temperature reaches above 500°C without the addition of zeolite, the volume of tar yields decreases because the primary tar begins to break down and forms secondary tar up to a temperature of 800°C when the primary tar has been used up [14]

Summary

Introduction

Pyrolysis is a method for converting biomass into fuel, whether as a solid, gas, or liquid fuel. Complex hydrocarbon molecules in biomass break down into relatively smaller and simpler gas, liquid, and carbon [1]. Other process is needed to break these long hydrocarbon compounds into simpler ones. There are two methods to decompose these complex biomass compounds: thermal cracking and catalytic cracking process. There has been plenty of research on thermal cracking, but research on catalytic cracking has not yet been done. In this study, both methods were used, though the catalytic cracking effect was focused more. Catalytic cracking is the process of breaking the chain of hydrocarbons into shortchained hydrocarbons with the help of a catalyst [2]

Methods

Results

Conclusion