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Effects of pretreatment with oxygen and oxygen-containing compounds on the catalytic behaviour of Pd-Ag catalyst for the selective hydrogenation of acetylene

หน่วยงาน จุฬาลงกรณ์มหาวิทยาลัย

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ชื่อเรื่อง : Effects of pretreatment with oxygen and oxygen-containing compounds on the catalytic behaviour of Pd-Ag catalyst for the selective hydrogenation of acetylene
นักวิจัย : Bongkot Ngamsom
คำค้น : Oxygen , Acetylene , Hydrogenation , Catalysts , Palladium
หน่วยงาน : จุฬาลงกรณ์มหาวิทยาลัย
ผู้ร่วมงาน : Piyasan Praserthdam , Trimm, David , Bogdanchikova, Nina , Chulalongkorn University. Faculty of Engineering
ปีพิมพ์ : 2545
อ้างอิง : 9741720599 , http://cuir.car.chula.ac.th/handle/123456789/1432
ที่มา : -
ความเชี่ยวชาญ : -
ความสัมพันธ์ : -
ขอบเขตของเนื้อหา : -
บทคัดย่อ/คำอธิบาย :

Thesis (D.Eng.)--Chulalongkorn University, 2002

Effects of pretreatment with oxygen and oxygen-containing compounds (NO, N[subscript 2]O, CO and CO[subscript 2]) on Pd-Ag catalysts for the selective hydrogenation of acetylene have been studied. Enhancement of the catalyst activity for C[subscript 2]H[subscript 2] removal has been found after pretreatment. However, only pretreatment with N[subscript 2]O and NO have revealed the improved ethylene gain. Catalysts have been characterised either on the bulk or surface aspects by various techniques, i.e., XRD, TEM, CO-adsorption, TPR, TPD, TPO, XPS and FT-IR. XRD and TEM suggest bulk phase of Pd-Ag alloy with diameter ca. 6.7 nm after reduction. Modification in the reducibility and hydrogen sorption properties of palladium was influenced by the presence of Ag. Surface analysis by XPS has confirmed the existence of surface Pd-Ag alloy with Ag enrichment after reduction. Pretreatment results in dilution of surface Ag enrichment, indicating from the smallerPd:Ag ratio (Palladium fraction becomes slightly increased 3-13.6%). Significant shift of the Ag 3d binding energy is revealed after NO and N[subscript 2]O pretreatment. The surface after reaction shows no state change of either Pd or Ag compared to those measured prior to reaction, therefore surface modification occurs after pretreatment and is retained after reaction for 8 h. No carbonaceous deposits is formed after 8 h on stream from TPO measurement and XPS. Infrared spectroscopy of NO and N[subscript 2]O treated samples shows the linear complex Pd-NO, nitrate and nitrite species on Ag-Al[subscript 2]O[subscript 3]. C[subscript 2]H[subscript 2] adsorption displays ethylidyne species which is sufficiently decreased by N[subscript 2]O pretreatment. Pretreatment with NO and N[subscript 2]O results in blockage of Pd sites responsible for direct ethane formation via ethylidyne species, ethylene gain is thus increased as a consequence. On the other hand, pretreatment with O[subscritp 2], CO or CO[subscript 2]increases dispersion of Pd on the support, which increases C[subscript 2]H[subscript 2] hydrogenation activity

บรรณานุกรม :
Bongkot Ngamsom . (2545). Effects of pretreatment with oxygen and oxygen-containing compounds on the catalytic behaviour of Pd-Ag catalyst for the selective hydrogenation of acetylene.
    กรุงเทพมหานคร : จุฬาลงกรณ์มหาวิทยาลัย.
Bongkot Ngamsom . 2545. "Effects of pretreatment with oxygen and oxygen-containing compounds on the catalytic behaviour of Pd-Ag catalyst for the selective hydrogenation of acetylene".
    กรุงเทพมหานคร : จุฬาลงกรณ์มหาวิทยาลัย.
Bongkot Ngamsom . "Effects of pretreatment with oxygen and oxygen-containing compounds on the catalytic behaviour of Pd-Ag catalyst for the selective hydrogenation of acetylene."
    กรุงเทพมหานคร : จุฬาลงกรณ์มหาวิทยาลัย, 2545. Print.
Bongkot Ngamsom . Effects of pretreatment with oxygen and oxygen-containing compounds on the catalytic behaviour of Pd-Ag catalyst for the selective hydrogenation of acetylene. กรุงเทพมหานคร : จุฬาลงกรณ์มหาวิทยาลัย; 2545.