KY-89 zeolitinde asitlik dağılımının ve bazı hidrokarbonların etkin difüzyon katsayılarının gaz kromatografi ile tayini
Küçük Resim Yok
Tarih
1987
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
IV ÖZET Bu çalışmada, hazırlanan bir KY-89 toz zeoliti üzerinde gaz kromatografik yöntemle 80-200°C sıcaklık aralığında piri- dinin adım adım ısıl desorpsiyonu yapılarak zeolitteki asi"" dik merkezlerin dağılımı ve yine gaz kromatografik yöntemle taneli KY-89 zeoliti üzerinde orto va para ksilenin 150, 165, 190°C sıcaklıklardaki etkin difüzyonu incelenmiştir. Hazırlanan KX-89 zeolitinin 80-200°ö sıcaklık aralığında-. ki asidik merkezlerinin zayıf asidik merkezler olduğu ve ter sinmez kimyasal adsorblanmış piridin miktarı-sıcaklık eğrisi nin literatüre uyduğu gözlenmiştir. Etkin difüzyon katsayıla rı hesaplanırken yüksek taşıyıcı gaz debileri seçilerek Van Deemter eşitliğinin doğrusal bölgesinde çalışma sağlanmış ve buradan etkin difüzyon katsayısının fonksiyonu olan G sabiti hesaplanmıştır. Daha sonra 0 sabiti ve K dağılma katsayısı kullanılarak orto ve para ksilenin 150,165 ve 190°C sıcak lıklardaki etkin difüzyon katsayıları (De) hesaplanmıştır. Elde edilen De değerleri literatürde orto ve para ksilen için 250, 500 ve 345°C sıcaklıklarda verilen etkin difüzyon katsa yıları ile karşılaştırılmış ve birbirleri ile uyum içinde ol dukları görülmüştür
SUMMARY In. this w>rk, the acidity distribution of a KY-89 type zeolite prepared from a NaX-zeolite has been investigated by gas chromatographic method and also the efective diffu-^ sivities of o-xylene and p-xylene in this catalyst -were measured using the same technique at; the temperatures of 150, 165 and 190°C. Gas chromatographic method for acidity distribution starts -with the sorption of pyridine on to the zeolite at 80°0, is folio-wed by desorption at elevated temperatures up to 200°C, employing a step-wise increase of temperature. It has been seen that the acid sites on this synthetic zeolite in the temperature range 80-200°C -were -weak acid sites and the curve obtained by plotting the irreversible chemisorbed amount of pyridine against temperature -was in agreement -with the literature. To be able^to use the linear region of the Van Deemter eq- uation for calculating the effective diffusivities of o-xylene and p-xylene in the zeolite, high volumetric flow- rates of the carrier gas -were selected and C term in this equation has been found. Using this term -which -was the function of effective diffusion coefficient and K -which ?was the dibtribution coefficient related to the chromatog raphic parameters, the effective diffusion coefficients of o-xylene and p-xylene have been obtained at 150, 165 and 190°0. These values calculated have been compared -with the effective diffusion coefficients given by the literature for o-xylene and p-xylene at 250, 500 and 3^5°0 and it has been seen that they -were in agreement -with eachother.
SUMMARY In. this w>rk, the acidity distribution of a KY-89 type zeolite prepared from a NaX-zeolite has been investigated by gas chromatographic method and also the efective diffu-^ sivities of o-xylene and p-xylene in this catalyst -were measured using the same technique at; the temperatures of 150, 165 and 190°C. Gas chromatographic method for acidity distribution starts -with the sorption of pyridine on to the zeolite at 80°0, is folio-wed by desorption at elevated temperatures up to 200°C, employing a step-wise increase of temperature. It has been seen that the acid sites on this synthetic zeolite in the temperature range 80-200°C -were -weak acid sites and the curve obtained by plotting the irreversible chemisorbed amount of pyridine against temperature -was in agreement -with the literature. To be able^to use the linear region of the Van Deemter eq- uation for calculating the effective diffusivities of o-xylene and p-xylene in the zeolite, high volumetric flow- rates of the carrier gas -were selected and C term in this equation has been found. Using this term -which -was the function of effective diffusion coefficient and K -which ?was the dibtribution coefficient related to the chromatog raphic parameters, the effective diffusion coefficients of o-xylene and p-xylene have been obtained at 150, 165 and 190°0. These values calculated have been compared -with the effective diffusion coefficients given by the literature for o-xylene and p-xylene at 250, 500 and 3^5°0 and it has been seen that they -were in agreement -with eachother.
Açıklama
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Anahtar Kelimeler
Kimya Mühendisliği, Chemical Engineering
