Influence of Support Structural Characteristics on Long-term Performance of Pd-Ag/α-Al2O3 Catalyst for Tail-end Acetylene Selective Hydrogenation

2016 ◽  
Vol 14 (5) ◽  
pp. 1035-1046 ◽  
Author(s):  
Maryam Takht Ravanchi ◽  
Saeed Sahebdelfar ◽  
Maryam Rahimi Fard
Keyword(s):  
Selective Hydrogenation ◽  
Catalyst Deactivation ◽  
Structural Characteristics ◽  
Coke Deposition ◽  
Main Reaction ◽  
Impregnation Method ◽  
Time Data ◽  
Egg Shell ◽  
Α Al2o3 ◽  
Acetylene Selective Hydrogenation

Abstract The selective hydrogenation of acetylene to ethylene in acetylene/ethylene mixture over Pd-Ag/α-Al2O3 catalysts prepared by sequential impregnation method was studied. The α-Al2O3 support was prepared by thermal treatment of γ-Al2O3 in temperature range of 1,090–1,100 °C. The samples were characterized for their structural properties and coke deposition. They showed egg-shell structure with penetration depth increasing with sintering temperature of the support. A kinetic model based on 1st order in acetylene and 0.5th order in hydrogen for the main reaction and 2nd order independent decay law for catalyst deactivation was used to fit the conversion-time data and to obtain quantitative assessment of catalyst performances. Fair fits were observed from which the reaction and deactivation rate constants were evaluated. The highest selectivity to ethylene, and therefore best performance, was obtained for the highest calcination temperature which was attributed to its lower acidity and larger pore diameters.

An alumina-coated, egg-shell Pd/α-Al2O3@SiC catalyst with enhanced ethylene selectivity in the selective hydrogenation of acetylene

RSC Advances ◽  
2016 ◽  
Vol 6 (62) ◽  
pp. 57174-57182 ◽  
Author(s):  
Huoli Zhang ◽  
Jianliang Cao ◽  
Baojun Wu ◽  
Wei Dai ◽  
Zehua Chen ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Complete Removal ◽  
Selective Hydrogenation Of Acetylene ◽  
Ethylene Selectivity ◽  
Egg Shell ◽  
Α Al2o3

The Pd–Ag/α-Al2O3@SiC catalyst showed higher ethylene selectivity than a Pd–Ag/α-Al2O3 catalyst when achieving complete removal of acetylene in an ethylene-rich stream.

scholarly journals Deactivation and Regeneration of Zeolite Catalysts Used in Pyrolysis of Plastic Wastes—A Process and Analytical Review

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 770
Author(s):  
Vivien Daligaux ◽  
Romain Richard ◽  
Marie-Hélène Manero
Keyword(s):  
Catalyst Deactivation ◽  
Structural Characteristics ◽  
Deep Understanding ◽  
Analytical Techniques ◽  
Reaction Rates ◽  
Zeolite Catalysts ◽  
Coke Deposition ◽  
Oh Radicals ◽  
Major Drawback ◽  
Solid Catalysts

In catalytic industrial processes, coke deposition remains a major drawback for solid catalysts use as it causes catalyst deactivation. Extensive study of this phenomenon over the last decades has provided a better understanding of coke behavior in a great number of processes. Among them, catalytic pyrolysis of plastics, which has been identified as a promising process for waste revalorization, is given particular attention in this paper. Combined economic and environmental concerns rose the necessity to restore catalytic activity by recovering deactivated catalysts. Consequently, various regeneration processes have been investigated over the years and development of an efficient and sustainable process remains an industrial challenge. Coke removal can be achieved via several chemical processes, such as oxidation, gasification, and hydrogenation. This review focuses on oxidative treatments for catalyst regeneration, covering the current progress of oxidation treatments and presenting advantages and drawbacks for each method. Molecular oxidation with oxygen and ozone, as well as advanced oxidation processes with the formation of OH radicals, are detailed to provide a deep understanding of the mechanisms and kinetics involved (direct and indirect oxidation, reaction rates and selectivity, diffusion, and mass transfer). Finally, this paper summarizes all relevant analytical techniques that can be used to characterize deactivated and regenerated solid catalysts: XRD, N2 adsorption-desorption, SEM, NH3-TPD, elemental analysis, IR. Analytical techniques are classified according to the type of information they provide, such as structural characteristics, elemental composition, or chemical properties. In function of the investigated property, this overall tool is useful and easy-to-use to determine the adequate analysis.

scholarly journals Effect of barium loading on CaO derived from waste egg shell heterogeneous catalyst for canola oil biodiesel

2018 ◽  
Vol 192 ◽  
pp. 03006
Author(s):  
Jakkrapong Jitjamnong
Keyword(s):  
Microwave Irradiation ◽  
Heterogeneous Catalyst ◽  
Canola Oil ◽  
Catalytic Performance ◽  
Biodiesel Production ◽  
Catalyst Loading ◽  
Impregnation Method ◽  
Egg Shells ◽  
Infrared Spectrometer ◽  
Egg Shell

The purpose of this research was to investigate the catalytic activity of Ba loading on calcium oxide (CaO) catalyst by varying the amount of barium added during the synthesis: 5-15 wt%. The waste egg shells were utilized as a CaO heterogeneous catalyst by calcined at 900 °C for 2 h. The Ba/CaO catalysts were prepared by impregnation method and were used as a catalyst in transesterification reaction of canola oil via microwave irradiation under microwave power 300 W. The characterization of catalyst and FAME composition of biodiesel were determined by X-ray fluorescence (XRF), scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), and gas chromatography (GC-FID). The conditions of biodiesel production were operated at 60 °C, 3 wt% of catalyst loading, 9:1 methanol-to-canola oil ratio, and microwave irradiation power was 300W for 2 min. The experimental results found that, the waste egg shells consist mainly of CaCO3, which was decomposed to CaO more than 88 wt% after cacination step. The 15 wt% Ba/CaO catalysts exhibited the best catalytic performance with the FAME conversion higher than 97.68%.

scholarly journals A General Fitting Function to Estimate Apparent Reaction Orders of Kinetic Profiles

2019 ◽  
Author(s):  
Robert Pollice
Keyword(s):  
Chemical Reactions ◽  
Catalyst Deactivation ◽  
Rapid Development ◽  
Product Inhibition ◽  
Time Profile ◽  
Time Data ◽  
Concentration Time ◽  
Wide Range ◽  
Reaction Orders

The rapid development of analytical methods in recent decades has resulted in a wide range of readily available and accurate reaction-monitoring techniques, which allow for easy determination of high-quality concentration-time data of chemical reactions. However, while the acquisition of kinetic data has become routine in the development of new chemical reactions and the study of their mechanisms, not all the information contained therein is utilized because of a lack of suitable analysis tools which unnecessarily complicates mechanistic studies. Herein, we report on a general method to analyze a single concentration-time profile of chemical reactions and extract information regarding the reaction order with respect to substrates, the presence of multiple kinetic regimes, and the presence of kinetic complexities, such as catalyst deactivation, product inhibition, and substrate decomposition.<br>

scholarly journals Acoustic televiewer logging in glacier boreholes

2000 ◽  
Vol 46 (155) ◽  
pp. 695-699 ◽  
Author(s):  
Roger H. Morin ◽  
Guillaume E. Descamps ◽  
L. DeWayne Cecil
Keyword(s):  
Acoustic Waves ◽  
Structural Characteristics ◽  
Physical Nature ◽  
Time Data ◽  
Cross Sectional ◽  
Additional Information ◽  
Geophysical Logging ◽  
Transit Times ◽  
Acoustic Images ◽  
Deformation Processes

AbstractThe acoustic televiewer is a geophysical logging instrument that is deployed in a water-filled borehole and operated while trolling. It generates a digital, magnetically oriented image of the borehole wall that is developed from the amplitudes and transit times of acoustic waves emitted from the tool and reflected at the water–wall interface. The transit-time data are also converted to radial distances, from which cross-sectional views of the borehole shape can be constructed. Because the televiewer is equipped with both a three-component magnetometer and a two-component inclinometer, the borehole’s trajectory in space is continuously recorded as well. This instrument is routinely used in mining and hydrogeologic applications, but in this investigation it was deployed in two boreholes drilled into Upper Fremont Glacier, Wyoming, U.S.A. The acoustic images recorded in this glacial setting are not as clear as those typically obtained in rocks, due to a lower reflection coefficient for water and ice than for water and rock. Results indicate that the depth and orientation of features intersecting the boreholes can be determined, but that interpreting their physical nature is problematic and requires corroborating information from inspection of cores. Nevertheless, these data can provide some insight into englacial structural characteristics. Additional information derived from the cross-sectional geometry of the borehole, as well as from its trajectory, may also be useful in studies concerned with stress patterns and deformation processes.

Acetylene-Selective Hydrogenation Catalyzed by Cationic Nickel Confined in Zeolite

2019 ◽  
Vol 141 (25) ◽  
pp. 9920-9927 ◽  
Author(s):  
Yuchao Chai ◽  
Guangjun Wu ◽  
Xiaoyan Liu ◽  
Yujing Ren ◽  
Weili Dai ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Acetylene Selective Hydrogenation

An egg-shell bifunctional CeO2-modified NiPd/Al2O3 catalyst for petrochemical processes involving selective hydrogenation and hydroisomerization

2020 ◽  
Author(s):  
Franklin J. Méndez ◽  
Javier A. Alves ◽  
Yahsé Rojas-Challa ◽  
Oscar Corona ◽  
Yanet Villasana ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Egg Shell ◽  
Al2o3 Catalyst

Research on Boom-Type Roadheader Vibration Testing Based on the LabVIEW

2011 ◽  
Vol 418-420 ◽  
pp. 1988-1991
Author(s):  
Li Juan Zhao ◽  
Xiu Mei Lv ◽  
Wei Tong
Keyword(s):  
Real Time ◽  
Detection System ◽  
Structural Characteristics ◽  
Test System ◽  
Vibration Characteristics ◽  
Acquisition Time ◽  
Vibration Source ◽  
Time Data ◽  
Vibration Signals ◽  
Time Frequency

This develops the roadheader vibration characteristics test system according to the structural characteristics and working principle of the cantilevered roadheader. Using the piezoelectric acceleration sensor detects vibration signal, and passing by signal processing and A/D conversion， vibration signals are sent to the PC with wireless transmission mode, vibration signals detected by the LabVIEW is realized real-time data acquisition, time-frequency analysis and digital processing. Based on this system testing results can effectively master roadheader operation state, identify the vibration characteristics, look for vibration source and put forward reasonable damping vibration measure, which provide the basis for roadheader in the best running condition. The development of roadheader vibration detection system uses the method that combines theory and simulation experiment , which realizes the real-time detection of roadheader vibration behavior, rational signal analysis of roadheader vibration and accurate processing of data results, it provides an important method to ensure the reliability of roadheader.

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