Effects of the support crystallite size and the reduction temperature on the properties of Pd/α-Al2O3 catalysts in selective acetylene hydrogenation

2008 ◽  
Vol 94 (2) ◽  
pp. 233-241 ◽  
Author(s):  
Sataporn Komhom ◽  
Piyasan Praserthdam ◽  
Okorn Mekasuwandumrong ◽  
Joongjai Panpranot
Keyword(s):  
Crystallite Size ◽  
Reduction Temperature ◽  
Acetylene Hydrogenation ◽  
Α Al2o3

scholarly journals An Experimental Approach on Industrial Pd-Ag Supported α-Al2O3 Catalyst Used in Acetylene Hydrogenation Process: Mechanism, Kinetic and Catalyst Decay

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 136
Author(s):  
Ourmazd Dehghani ◽  
Mohammad Rahimpour ◽  
Alireza Shariati
Keyword(s):  
Kinetic Model ◽  
Experimental Approach ◽  
Catalyst Deactivation ◽  
Catalyst Activity ◽  
Hydrogenation Process ◽  
Support Surface ◽  
Acetylene Hydrogenation ◽  
Wide Range ◽  
Α Al2o3 ◽  
Al2o3 Catalyst

The current research presents an experimental approach on the mechanism, kinetic and decay of industrial Pd-Ag supported α-Al2O3 catalyst used in the acetylene hydrogenation process. In the first step, the fresh and deactivated hydrogenation catalysts are characterized by XRD, BET (Brunauer–Emmett–Teller), SEM, TEM, and DTG analyses. The XRD results show that the dispersed palladium particles on the support surface experience an agglomeration during the reaction run time and mean particle size approaches from 6.2 nm to 11.5 nm. In the second step, the performance of Pd-Ag supported α-Al2O3 catalyst is investigated in a differential reactor in a wide range of hydrogen to acetylene ratio, temperature, gas hourly space velocity and pressure. The full factorial design method is used to determine the experiments. Based on the experimental results ethylene, ethane, butene, and 1,3-butadiene are produced through the acetylene hydrogenation. In the third step, a detailed reaction network is proposed based on the measured compounds in the product and the corresponding kinetic model is developed, based on the Langmuir-Hinshelwood-Hougen-Watson approach. The coefficients of the proposed kinetic model are calculated based on experimental data. Finally, based on the developed kinetic model and plant data, a decay model is proposed to predict catalyst activity and the parameters of the activity model are calculated. The results show that the coke build-up and condensation of heavy compounds on the surface cause catalyst deactivation at low temperature.

A novel configuration for Pd/Ag/α-Al2O3 catalyst regeneration in the acetylene hydrogenation reactor of a multi feed cracker

2012 ◽  
Vol 198-199 ◽  
pp. 491-502 ◽  
Author(s):  
M.R. Rahimpour ◽  
O. Dehghani ◽  
M.R. Gholipour ◽  
M.S. Shokrollahi Yancheshmeh ◽  
S. Seifzadeh Haghighi ◽  
...  
Keyword(s):  
Catalyst Regeneration ◽  
Acetylene Hydrogenation ◽  
Α Al2o3 ◽  
Hydrogenation Reactor ◽  
Al2o3 Catalyst

scholarly journals Oryza sativa PULP AS A TEMPLATE IN α-ALUMINA NANOCRYSTALLINE SYNTHESIS BY PRECURSOR CALCINING PROCESS

2016 ◽  
Vol 1 (01) ◽  
Author(s):  
Rifki Septawendar ◽  
Bambang Sunendar Purwasasmita ◽  
Suhanda , ◽  
Leanddas Nurdiwijayanto ◽  
Taufan Hidayat
Keyword(s):  
Oryza Sativa ◽  
Crystallite Size ◽  
Calcination Temperature ◽  
Sol Gel ◽  
Weight Ratio ◽  
Xrd Analysis ◽  
Characterization Result ◽  
Nano Powder ◽  
Temperature Scanning ◽  
Α Al2o3

Synthesis and characterization of α-alumina nano powder with Oryza sativa pulp as template by precursor calcining process have been successfully conducted. The aim of this experiment is to study the potential of Oryza sativa pulp as a template of precursor calcining process method that isrelatively cheaper than that of sol gel method in α-alumina synthesis. Weight ratio between precursor and Oryza sativa pulp was 1 : 2. The effect of calcination temperature on α-alumina synthesis in this research is set by variation of calcination temperature at 900°C, 1000°C, and 1100°C. In this research, X-Ray Diffraction (XRD) analysis is used to investigate the transformation of crystal phase, structure and size of the crystal formed by the calcinations temperature. Scanning Electron Microscope (SEM)characterization is used to identify morphology of α-Al2O3 powder. Based on XRD characterization result, synthesized alumina sample forms α-Al2O3 and γ-Al2O3 crystal phases. The formed crystallite size is in nanometer dimension for α-Al2O3 which biggest crystallite size is 46.6 nm. According to SEM characterization result, it is shown that α-Al2O3 formed rhombohedral or bar shape and planar. The particle size will increase along with the elevation of calcination temperature.Key words : nano powder, α-alumina, precursor calcining process, oryza sativa pulp ABSTRAKSintesis dan karakterisasi nanopowder α-alumina dengan menggunakan pulp merang sebagai template melalui proses kalsinasi prekursor telah berhasil dilakukan. Penelitian ini bertujuan untuk mempelajari potensi pulp merang sebagai template dari precursor calcination process yang merupakan metoda relatif lebih murah dibandingkan metode sol gel dalam mensintesis α-alumina. Perbandingan berat antara prekursor dan pulp adalah 1:2. Pengaruh temperatur kalsinasi terhadap pembentukan α-alumina ditetapkan dengan variasi temperatur kalsinasi pada 900°C, 1000°C, dan 1100°C. Analisis diffraksi Sinar-X (XRD) digunakan untuk mengetahui perubahan fasa kristal, struktur, dan ukuran kristal yangterbentuk pada suhu kalsinasi tersebut. Karakterisasi SEM dilaksanakan untuk mengetahui morfologi dari serbuk α-Al2O3. Berdasarkan karakterisasi XRD, sampel alumina yang disintesis membentuk fasa α-Al2O3 dan γ-Al 2O3. Ukuran kristal yang terbentuk berskala nanometer, yaitu untuk α-Al2O3 ukuran kristal terbesar adalah 46,6 nm. Hasil karakterisasi SEM, terlihat bahwa α-Al2O3 membentuk struktur trigonal atau bentuk batang dan planar, ukuran partikel akan semakin membesar dengan meningkatnyatemperatur kalsinasi.Kata kunci : nano powder, α-alumina, proses kalsinasi prekursor, pulp merang. 

The Role of Coke in Acetylene Hydrogenation on Pd/α-Al2O3

1998 ◽  
Vol 178 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Mikael Larsson ◽  
Jonas Jansson ◽  
Staffan Asplund
Keyword(s):  
Acetylene Hydrogenation ◽  
Α Al2o3

Effect of Fe-modified α-Al2O3 on the properties of Pd/α-Al2O3 catalysts in selective acetylene hydrogenation

2009 ◽  
Vol 97 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Tatiya Sangkhum ◽  
Okorn Mekasuwandumrong ◽  
Piyasan Praserthdam ◽  
Joongjai Panpranot
Keyword(s):  
Acetylene Hydrogenation ◽  
Α Al2o3

scholarly journals SINTESA AL2O3 DARI SERBUK BOEHMITE MENGGUNAKAN TEKNIK SPARK PLASMA SINTERING (SPS): STUDI TRANSFORMASI FASA, MIKROSTRUKTUR DAN KEKERASAN

Metalurgi ◽  
2020 ◽  
Vol 35 (2) ◽  
pp. 65
Author(s):  
Diastati Puspita Ning Ayu ◽  
Bambang Hermanto ◽  
Arif Tjahjono ◽  
Toto Sudiro
Keyword(s):  
Dislocation Density ◽  
Crystallite Size ◽  
Spark Plasma Sintering ◽  
Lattice Strain ◽  
Vickers Microhardness ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Α Al2o3

Pada studi ini, telah disintesa bulk alumina dari serbuk boehmite menggunakan teknik spark plasma sintering (SPS) pada temperatur 650oC, 750oC, 950oC, 1100oC, 1200oC dan 1300oC. Transformasi fasa dari boehmite menjadi α-Al2O3, mikrostruktur dan sifat mekaniknya dipelajari pada rentang temperatur 650-1300oC. Struktur fasa yang terbentuk dianalisa dengan X-ray diffractometer (XRD), dan nilai crystallite size, lattice strain serta dislocation density di hitung berdasarkan hasil analisa puncak difraksi XRD. Morfologi permukaan sampel diobservasi dengan menggunakan alat optical micoscope (OM). Karakteristik mekanik sampel yang terdiri atas nilai kerapatan massa dan kekerasan sampel masing-masing diukur menggunakan prinsip Archimedes dan vickers microhardness. Hasil XRD menunjukkan bahwa -alumina mulai terbentuk pada temperatur 1100oC, namun masih terdapat struktur lain yaitu -alumina. Struktur -alumina terbentuk sempurna pada temperatur 1300oC. Hasil perhitungan menunjukkan bahwa nilai crystallite size berbanding terbalik dengan nilai lattice strain dan dislocation density. Analisa mikrostruktur dengan menggunakan OM menunjukkan bahwa pada temperatur 650oC dan 750oC sampel belum homogen. Nilai kekerasan dan kerapatan massa sampel meningkat seiring dengan kenaikan temperatur sintering.

Direct Observation of Crystalline Ordering In Naturally Graphitized Carbon Produced by Low Grade Metamorphism

1977 ◽  
Vol 35 ◽  
pp. 162-163
Author(s):  
Thomas R. McKee ◽  
Peter R. Buseck
Keyword(s):  
Crystallite Size ◽  
Sedimentary Rocks ◽  
Carbonaceous Material ◽  
Low Grade ◽  
X Ray ◽  
Graphitized Carbon ◽  
Transmission Electron ◽  
Heat Treated ◽  
Commercial Carbon ◽  
Metamorphic Zone

Sediments commonly contain organic material which appears as refractory carbonaceous material in metamorphosed sedimentary rocks. Grew and others have shown that relative carbon content, crystallite size, X-ray crystallinity and development of well-ordered graphite crystal structure of the carbonaceous material increases with increasing metamorphic grade. The graphitization process is irreversible and appears to be continous from the amorphous to the completely graphitized stage. The most dramatic chemical and crystallographic changes take place within the chlorite metamorphic zone.The detailed X-ray investigation of crystallite size and crystalline ordering is complex and can best be investigated by other means such as high resolution transmission electron microscopy (HRTEM). The natural graphitization series is similar to that for heat-treated commercial carbon blacks, which have been successfully studied by HRTEM (Ban and others).

Effect of the structural changes on the mechanical properties of the sintered films

2016 ◽  
Vol 12 (1) ◽  
pp. 4141-4144
Author(s):  
Garima Jain
Keyword(s):  
Crystallite Size ◽  
Lattice Constant ◽  
Structural Changes ◽  
Structural Investigation ◽  
Energy Gap ◽  
Lattice Parameter ◽  
Metal Chalcogenides ◽  
Optical Energy Gap ◽  
Tin Telluride ◽  
Physical Quantities

Polycrystalline films of tin telluride were prepared by sintering technique. The structural investigation of the films with different thicknesses enables to determine lattice parameter, crystallite size and strain existing in the films. The XRD traces showed that strain was tensile in nature. The crystallite size increases with thickness while strain decreases. Higher the value of tensile strain, larger is the lattice constant. The optical energy gap shows a descending nature with increasing strain and so with the lattice constant. Such an attempt made to delve into interdependence of basic physical quantities helps to explore the properties of SnTe and utilize it as an alternative to heavy metal chalcogenides in various technological applications.  

Sign in / Sign up

Export Citation Format

Share Document