Akeem Azeez - Effects of zeolites on volatile products of beech wood using analytical pyrolysis

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      Article Outline

            Materials and methods 
        2.1.     Catalyst 
        2.2.     Biomass 
        2.3.     Pyrolysis-GC/MS/FID 
        2.4.     Data treatment 
            Results and discussion 
        3.1.     Effects of catalyst type 
        3.2.     Effect of catalyst concentration 


      Five unmodified basic and acidic zeolites have been tested in the   thermo-chemical conversion of beech (Fagus sylvatica L.)   using an on-line pyrolysis-gas chromatography/mass spectrometry   (Py-GC/MS) system to study their effects on lignocellulose   thermal degradation products. The catalysts employed were SN-27,   MSN-15, MSM-15, H-ZSM-5-28 and H-ZSM-5-80 with varying Si/Al   ratio between 11 and 80. Thoroughly mixed samples of the biomass   with different catalysts loading were pyrolysed at 500 °C. The   catalyst exhibited varying degree of selectivity on individual   volatile products. The selectivity was largely controlled by the   nature of zeolites’ active sites and alumina contents. The acidic   catalysts mostly influenced the condensable organic products;   induced high yields of furfural and levoglucosan. Their yields   increased up to five and nine times respectively in samples   spiked with 40% MSM-15 and H-ZMS-5 on the basis of feedstock   weight. H-ZSM-5 with lower alumina content proved most effective   in enhancing high yield of furfural due to better diffusion of   molecules through the pores. A slight reduction in polysaccharide   derived low molecular volatiles such as hydroxyacetaldehyde,   acetic acid, hydroxypropanone was observed in all catalysts. The   overall result indicated that the acidic catalysts largely   induced cleavage of glycosidic bonds through protonation   predominantly on zeolites’ surface area. This was followed by the   modification of free hydroxyl groups through dehydration process.   All zeolites revealed no significant effect on most lignin   derived products except indenes.

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