Pt–Sn-based catalyst’s intensification using Al2O3–SAPO-34 as a support for propane dehydrogenation to propylene

Zeeshan Nawaz,Fei Wei 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.3

The addition of Al_2O_3 up to 20% (as cementing agent) in SAPO-34 support significantly integrates metal functions of Pt–Sn-based catalyst, ultimately improves catalytic performance for direct propane dehydrogenation to propylene. Superior propane conversion (initially above 40%) and propylene selectivity (around 95%) is obtained experimentally over Pt–Sn/Al_2O_3–SAPO-34. The results were found promising and compared with Pt–Sn/SAPO-34 under identical operating conditions. Better platinum dispersion and higher active platinum sites are characterized by TEM and hydrogen-chemisorption analysis. Moreover, the possible metal interactions with different supports were configured. Therefore,light alkane dehydrogenation to alkene was enhanced using surface modified support Al_2O_3–SAPO-34for Pt–Sn-based catalysts.

Influence of operating conditions, Si/Al ratio and doping of zinc on Pt-Sn/ZSM-5 catalyst for propane dehydrogenation to propene

Zeeshan Nawaz,Tang Xiaoping,Fei Wei 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

The direct catalytic dehydrogenation of propane to propene is an important route to enhance propene production. In the present experimentation the focus was to investigate the influence of incipient operating conditions, Si/Al ratio of zeolite support and effect of zinc doping on Pt-Sn/ZSM-5 catalyst performance. The catalysts were extensively investigated by reaction tests in a continuous plug-flow quartz micro-reactor. The experimental data shows that the manipulation of operating parameters significantly improves the reaction performance, while huge dynamicity is observed in product distribution. Reaction temperature, 600℃ is found to be most suitable, while increasing the weight hourly space velocity (WHSV), propene selectivity improves at the expense of lower conversion. The OPE was drawn to observe overall reaction network. It was found that the acidity of zeolitic support plays a more important role in achieving desired product selectivity than additional metallic content. Accordingly, the Si/Al ratio of the ZSM-5 zeolite the pro- pene selectivity was enhanced, leading to remarkable improvement in the total olefins selectivity which was remarkably improved owing to a suppression of secondary reactions. At Si/Al ratio 300, the selectivity of propene and total olefins becomes stable at 73% and 90% respectively. The doping of Zn on Pt-Sn/ZSM-5 improves only propene selectivity, but is severely affected by quick deactivation.

Attrition behavior of fine particles in a fluidized bed with bimodal particles: Influence of particle density and size ratio

Zeeshan Nawaz,Tang Xiaoping,Xiaobo Wei,Fei Wei 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.5

To process the solid particulates in fluidized bed and slurry phase reactors, attrition is an inevitable consequence and is therefore one of the preliminary parameters for the catalyst design. In this paper, the mechanical degradation propensity of the zeolite catalysts (particles) was investigated in a bimodal distribution environment using a Gas Jet Attrition - ASTM standard fluidized bed test (D-5757). The experimentation was conducted in order to explore parameters affecting attrition phenomena in a bimodal fluidization. In a bimodal fluidization system, two different types of particles are co-fluidized isothermally. The air jet attrition index (AJI) showed distinct increases in the attrition rate of small particles in a bimodal fluidization environment under standard operating conditions, in comparison with single particle. A series of experiments were conducted using particles of various sizes, with large particles of different densities and sizes. Experimental results suggest that the relative density and particle size ratio have a significant influence on attrition behavior during co-fluidization. Therefore a generalized relationship has been drawn using Gwyn constants;those defined material properties of small particles. Moreover, distinct attrition incremental phenomenon was observed during co-fluidization owing to the change in collision pattern and impact, which was associated with relative particle density and size ratios.

Dehydrogenation of C3–C4 paraffin’s to corresponding olefins over slit-SAPO-34 supported Pt-Sn-based novel catalyst

Zeeshan Nawaz,Faisal Baksh,Jie Zhu,Fei Wei 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2

The objective of this work is to discuss the performance of Pt-Sn/slit-SAPO-34 novel catalyst for selective C3–C4 dehydrogenation to corresponding light olefins. The metallic contents, acidity, active metallic sites and metallic dispersion were determined using a number of physico-chemical techniques as it gives a justification for superior catalytic activity for dehydrogenation reaction. The Pt-Sn/slit-SAPO-34 catalyst was analyzed for dehydrogenation activity under optimized operating conditions; at atmospheric pressure, hydrogen to alkane (feed) molar ratio is 0.2, weight hourly space velocity 5 h1 and temperature 585 8C. Around 40% light alkane conversion and above 95% of total olefins selectivity with 94% propene, 92% n-butene and about 84% iso-butene selectivity were achieved over Pt-Sn/slit-SAPO-34novel catalyst. The catalyst was parametrically characterized over the above said operating conditions and effects of operating conditions on product distribution were discussed. The coke formation was inherently related to catalyst activity in dehydrogenation reaction and related to surface intermetallic ensemble effects; and ultimately the prominent stakeholder in catalyst deactivation. The novel catalysts also showed very good hydrothermal stability in a continuous reaction–regeneration cycles due to silicabased acidic structure of support. The results obtained over Pt-Sn/slit-SAPO-34 novel catalyst were compared with other Pt-Sn-based ZSM-5 and SAPO-34 supported catalysts of similar active metallic content under identical operating conditions.

Effect of Si/Al ratio on performance of Pt–Sn-based catalyst supported on ZSM-5 zeolite for n-butane conversion to light olefins

Zeeshan Nawaz,Shu Qing,Gao Jixian,Xiaoping Tang,Fei Wei 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.1

The performance of Pt–Sn-based catalyst, supported on ZSM-5 of different Si/Al ratios were investigated for simultaneous dehydrogenation and cracking of n-butane to produce light olefins. The catalysts were characterized by number of physio-chemical techniques including XRF, TEM, IR spectra, NH3-TPD and O2-pulse analysis. Increase in Si/Al ratio of zeolite support ZSM-5 significantly increased light olefin’s selectivity, while feed conversion decreases due to lower acidity of support. The results indicated that both the n-butane cracking and dehydrogenation activity to light olefin’s over Pt–Sn/ZSM-5 samples with increasing Si/Al ratios greatly enhanced catalytic performance. The catalysts were deactivated with time-on-stream due to the formation of carbon-containing deposits. A coke deposition was significantly related to catalyst activity, while at higher Si/Al ratio catalyst the coke precursors were depressed. These results suggested that the Pt–Sn/ZSM-5 catalyst of Si/Al ratio 300 is superior in achieving high total olefins selectivity (above 90 wt.%). The Pt–Sn/ZSM-5 also demonstrates resistance towards hydrothermal treatment, as analyzed through the three successive reaction-regeneration cycles.

Hydrothermal study of Pt–Sn-based SAPO-34 supported novel catalyst used for selective propane dehydrogenation to propylene

Zeeshan Nawaz,Fei Wei 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.5

Catalyst’s regeneration is unavoidable part during dehydrogenation. The hydrothermal treatment influence on the performance of Pt–Sn-based SAPO-34 supported novel catalyst, used for propane dehydrogenation to propylene is investigated in this study. The catalyst shows excellent stability for mild steaming (nitrogen mixed steam), during four consecutive runs (reaction–regeneration mode). On the other hand, Pt–Sn/ZSM-5 was largely affected on mild steaming due to severe dealumination. In order to get into mechanistic understanding, severe hydrothermal treatment was carried our using pure steam. The substation loss in catalyst activity was noted. Both fresh and severe hydrotreated catalysts were characterized by XRD, XRF, O2-pulse analysis of coke, NH3-TPD, IR spectrum of adsorbed ammonia,H2-TPR, HR-TEM and XPS, to explore reasons for change in catalytic properties. The texture/topology is found stable. Changes in surface ensembles occur due to the loss of Sn, Al, formation of SnOx species and in particular Pt sintering. This leads Pt active sites (zeolite–SnO–Pt) to inactive sites (zeolite–Pt, zeolite–PtO–Sn, Pt–Sn alloy, etc.) formation and reduced catalyst activity. TEM micrographs and H2-chemisorption analysis confirms Pt particles agglomeration and/or sintering. About 98% catalyst activity is recovered by re-dispersed Pt using chlorination technique and credit goes to hydrothermally stable support (SAPO-34). 2010 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Fault Diagnosis in Semiconductor Etch Equipment Using Bayesian Networks

Nawaz, Javeria Muhammad,Arshad, Muhammad Zeeshan,Hong, Sang Jeen The Institute of Electronics and Information Engin 2014 Journal of semiconductor technology and science Vol.14 No.2

A Bayesian network (BN) based fault diagnosis framework for semiconductor etching equipment is presented. Suggested framework contains data preprocessing, data synchronization, time series modeling, and BN inference, and the established BNs show the cause and effect relationship in the equipment module level. Statistically significant state variable identification (SVID) data of etch equipment are preselected using principal component analysis (PCA) and derivative dynamic time warping (DDTW) is employed for data synchronization. Elman's recurrent neural networks (ERNNs) for individual SVID parameters are constructed, and the predicted errors of ERNNs are then used for assigning prior conditional probability in BN inference of the fault diagnosis. For the demonstration of the proposed methodology, 300 mm etch equipment model is reconstructed in subsystem levels, and several fault diagnosis scenarios are considered. BNs for the equipment fault diagnosis consists of three layers of nodes, such as root cause (RC), module (M), and data parameter (DP), and the constructed BN illustrates how the observed fault is related with possible root causes. Four out of five different types of fault scenarios are successfully diagnosed with the proposed inference methodology.

Fault Detection in the Semiconductor Etch Process Using the Seasonal Autoregressive Integrated Moving Average Modeling

( Muhammad Zeeshan Arshad ),( Javeria Muhammad Nawaz ),( Sang Jeen Hong ) 한국정보처리학회 2014 Journal of information processing systems Vol.10 No.3

In this paper, we investigated the use of seasonal autoregressive integrated moving average (SARIMA) time series models for fault detection in semiconductor etch equipment data. The derivative dynamic time warping algorithm was employed for the synchronization of data. The models were generated using a set of data from healthy runs, and the established models were compared with the experimental runs to find the faulty runs. It has been shown that the SARIMA modeling for this data can detect faults in the etch tool data from the semiconductor industry with an accuracy of 80% and 90% using the parameter-wise error computation and the step-wise error computation, respectively. We found that SARIMA is useful to detect incipient faults in semiconductor fabrication.

Recurrent Neural Network Modeling of Etch Tool Data

Javeria Nawaz,Muhammad Zeeshan Arshad,Jinsu Park,Sungwon Shin,Sang Jeen Hong 한국진공학회 2012 한국진공학회 학술발표회초록집 Vol.2012 No.2

Process Fault Probability Generation via ARIMA Time Series Modeling of Etch Tool Data

Muhammad Zeeshan Arshad,Javeria Nawaz,Jinsu Park,Sungwon Shin,Sang Jeen Hong 한국진공학회 2012 한국진공학회 학술발표회초록집 Vol.2012 No.2