Termal analiz ile birleştirilmiş spektral yöntemlerin kullanımı ile biyokütle pirolizinin incelenmesi

Bu çalışmada badem kabuklarının TGA/FT-IR/MS sistemi ile pirolizi gerçekleştirilerek piroliz kinetiği ve açığa çıkan gazların analizi gerçekleştirilmiştir. Piroliz sırasında dört farklı ısıtma hızı uygulanmış ve elde edilen TG ve dTG eğrilerinden aktif piroliz bölgesi tespit edilmiştir. Isıtma hızlarının artması ile TG ve dTG eğrileri daha yüksek sıcaklık bölgelerine kaymış ve hesaplanan reaktivite değerleri artmıştır. Elde edilen veriler ile, dağılmış aktivasyon enerjisi yöntemi (DAEM) kullanılarak kinetik parametreler hesaplanmıştır. Hesaplamalar sonucunda ortalama aktivasyon enerjisi 166,4 kj/mol olarak bulunurken, aktivasyon enerjisinin dönüşüm kesri ile değişimi, piroliz sırasında karmaşık tepkime mekanizmalarının meydana geldiğini göstermiştir. Aktivasyon enerjisi değerleri iki farklı eş-dönüşüm yöntemi (Friedman ve FWO) kullanılarak da hesaplanmış ve elde edilen sonuçlar DAEM ile karşılaştırılmıştır. Farklı modeller kullanılması ile elde edilen tutarlı sonuçlar DAEM ile hesaplanan kinetik parametrelerin, badem kabuklarının pirolizini ifade etmekte kullanılabileceğini göstermiştir. Ayrıca, pirolitik bozunma sonucu açığa çıkan uçucular karşılaştırmalı olarak TGA/FT-IR ve TGA/MS ile tespit edilmiş ve bu uçucuların sıcaklığa bağlı salınımları izlenmiştir.

Investigation of biomass pyrolysis by using spectral methods combined with thermal analysis

In this study, pyrolysis of almond shells was performed by TGA/FT-IR/MS system and pyrolysis kinetics and evolved gas analysis were carried out. During pyrolysis, four different heating rates were applied and the active pyrolysis zone was determined from the obtained TG and dTG curves. With increasing heating rates, the TG and dTG curves shifted to higher temperature zones and the calculated reactivity values increased. Kinetic parameters were calculated by using the distributed activation energy method (DAEM) with the obtained data. As a result of calculations, the change of the activation energy with the conversion degree has shown that complex reaction mechanisms have occurred during pyrolysis while average activation energy was found as 166,4 kj/mol. Activation energy values were also calculated using two different iso-conversional methods (Friedman and FWO) and the results were compared with DAEM. Consistent results obtained using different models showed that kinetic parameters calculated by DAEM can be used to express pyrolysis of almond shells. In addition, volatiles released as a result of pyrolytic decomposition were detected by TGA/FT-IR and TGA/MS and their temperature-dependent evolutions were monitored.

Keywords:

Pyrolysis, kinetic biomass, evolved gas analysis almond shell,

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