An investigation on the role of a Pt/Al2O3 catalyst in the oxidative dehydrogenation of propane in annular reactor (original) (raw)
Related papers
2010
2 O 3 ; Propylene production One of the important light alkenes as an advantageous intermediate in the manufacture of polyme s and chemicals is propylene. Nowadays, most of propylene is generated as a byproduct o f gaso line production; therefore, the gasoline market demands determine the quantity of pro pylene production. Catalytic dehydrogenatio n of the pro pane is the most selective and conventional route to pro duce this short-chain alkene which has the potential to compensate the sho rtfall o f propylene left by gasoline plants. Industrial dehydrogenation processes use platinum-based catalysts generally supported on alumina and promo ted h Sn. The biggest dehydrogenation unit in Iran has been established in MTBE plant o f BIPC (Bandar Imam Petrochemical Complex) which producing Isobutene from Isobutane by exploiting a commercial catalyst: Pt-Sn-K/Al 2 O 3 (DP-803). In order to feasibility study of propylene pro ductio n rather than Isobutene in this plant, as a prim ary study, some bench-scale reaction tests were perfo rmed on the mentioned catalyst with H 2 /C 3 H 8 as reactants. Fo r the purpose of obtaining the operational conditions, 6 g catalyst were packed in a fixed-bed quartz reactor with the ID o f 10 mm and the length of 62 cm, and then reduced in mixed H 2 /N 2 with a kind of stepwise method. The effects of temperature, WHSV and H 2 /C 3 H 8 ratio were investigated on conversion and yield of propylene. Designing o f the experiments by choosing of one parameter at a time method, 27 runs were accomplished under the reaction temperature range o f 610 to 630 ? C, WHSVs of 2 to 4, H 2 /C 3 H 8 ratio s of 0.6 to 0.8; and atmospheric pressure. Acco rding to data analysis and obtained results, conversion of reactants, yield o f propylene on Pt-Sn-K /Al 2 O 3 (DP-803) attained a maximum value at 34%, when the operational condition were 630 ? C, H 2 /C 3 H 8 = 0.6; and WH SV= 3 hr -1 . γ γ 3
Chemical Engineering & Technology, 2015
Catalytic paraffin dehydrogenation for manufacturing olefins is considered to be one of the most significant production routes in the petrochemical industries. A reactor kinetic model for the dehydrogenation of propane to propylene in a radial-flow reactor over Pt-Sn/Al 2 O 3 as the catalyst was investigated here. The model showed that the catalyst activity was highly time dependent. In addition, the component concentrations and the temperature varied along the reactor radius owing to the occurring endothermic reaction. Moreover, a similar trend was noticed for the propane conversion as for the propylene selectivity, with both of them decreasing over the time period studied. Furthermore, a reversal of this trend was also revealed when the feed temperature was enhanced or when argon was added into the feed as an inert gas.
Journal of Catalysis, 2001
The oxidative dehydrogenation of ethane over a Pt/γ-Al 2 O 3 catalyst in adiabatic conditions (that is at T = 800−1000 • C and few milliseconds contact time) resulted in the production of ethylene with 50% yield. In order to better elucidate the single roles that gasphase reactions and heterogeneous phase reactions might play in the high-temperature activation of ethane, a detailed experimental and theoretical investigation was addressed. The results suggested that the performance of the adiabatic reactor relied on a cooperation between catalytic reactions (responsible for deep and partial oxidation of ethane to CO x , H 2 O, and H 2) and homogeneous reactions (responsible for the formation of olefins). In autothermal conditions, thus, the main function of the Pt-catalyst appeared to be that of accelerating ignition of the radical process, through the initial combustion of ethane which can occur at temperatures as low as 200 • C. It was demonstrated that the same function can be equally well accomplished by a Pt-free oxidation catalyst like the BaMnAl 11 O 19 which is active in the deep oxidation of ethane. Even in the presence of the hexa-aluminate material, which has no activity in the selective oxidation of ethane to ethylene, yields to ethylene higher than 50% were observed in the autothermal reactor by preheating the ethane/air feed stream at a proper temperature.
Chemical Engineering Science, 1994
Methylcyclohexane (MCH) has been proposed as a potentially attractive vector for hydrogen storage. For use in transportation, hydrogen when stored as MCH, needs to he liberated by dehydrogenation (endothermic reaction) in a compact catalytic reactor. By coupling the reactor with the engine, the waste heat could be utilized to run the reaction. Industrial Pt-Sn]Al203 catalyst was chosen as suitable for the reaction_ In this paper, a global model for the performance of the dehydrogenation reactor is developed. This model combines the kinetic models for the MCH dehydrogenation, and for the deactivation of the industrial Pt-Sn/AI203 catalyst, and the bidimensional model for a tubular reactor. In addition, new experimental data, compared with those predicted by the global model are presented.
Dehydrogenation of propane on modified Pt/θ-alumina Performance in hydrogen and steam environment
Applied Catalysis A: General, 2001
Dehydrogenation of propane was carried out on several promoted Pt catalysts. The performance of the catalysts (activity, selectivity and coke formation) was compared in steam and hydrogen environment. Promoting Pt supported on -alumina with Sn and K is essential for developing high-performance catalysts. The combination of optimal catalyst composition and steam yields high activity and selectivity at low coke formation. Inferior results were measured with hydrogen as diluent. Characterization of catalysts using XPS, TEM and chemisorption methods supported the results of reaction data.
Propane Dehydrogenation With Better Stability By A Modified Pt-Based Catalyst
2015
The effect of transition metal doping on Pt/Al2O3<br> catalyst used in propane dehydrogenation reaction at 500°C was<br> studied. The preparation methods investigated were sequential<br> impregnation (Pt followed by the 2nd metal or the 2nd metal followed<br> by Pt) and co-impregnation. The metal contents of these catalysts<br> were fixed as the weight ratio of Pt per the 2nd metal of around 0.075.<br> These catalysts were characterized by N2-physisorption, TPR, COchemisorption<br> and NH3-TPD. It was found that the impregnated 2nd<br> metal had an effect upon reducibility of Pt due to its interaction with<br> transition metal-containing structure. This was in agreement with the<br> CO-chemisorption result that the presence of Pt metal, which is a<br> result from Pt species reduction, was decreased. The total acidity of<br> bimetallic catalysts is decreased but the strong acidity is slightly<br> increased....
Deactivation of a Pt/γ-Al2O3 catalyst in the partial oxidation of methane to synthesis gas
Applied Catalysis A: General, 2003
The deactivation of a Pt/␥-Al 2 O 3 catalyst used in an industrial plant for the partial oxidation of methane to synthesis gas was investigated. Four samples at different time-on-stream in air were characterized and their catalytic performances were tested in a micro-reactor in order to shed light on the causes and the effects of this deactivation. The high temperatures (about 900 • C) reached while operating in the industrial plant, promoted modifications to the ␥-Al 2 O 3 , inducing sintering phenomena and, therefore, deactivation effects. The not used sample showed good values of yield in syngas (compared with equilibrium values), but these performances decreased quickly with time-on-stream.
Low-temperature oxidation reactions of ethane over a Pt/Al2O3 catalyst
Journal of Catalysis, 2003
Oxidative dehydrogenation of ethane was performed under conventional microreactor and TAP reactor conditions over a Pt/Al 2 O 3 catalyst between 100 and 600 • C. During TAP studies, no ethene was produced whereas under flow conditions small but significant ethene formation was observed. This is consistent with a mechanism involving the gas-phase production of ethene rather than via a surface reaction. In comparison, both hydrogen and methane formation were found under TAP conditions and the trends with temperature and surface oxide composition are interpreted in terms of successive dehydrogenation steps on the catalyst surface. It is further observed that periodic introduction of the reactants can minimize deactivation processes.
Catalysis Today, 2003
The effects of adding a co-metal, Pt or Rh, to Pd/␥-Al 2 O 3 catalysts were studied with respect to the catalytic activity for methane combustion and compared to a Pd/␥-Al 2 O 3 catalyst, using both a pressurized pilot-scale and a lab-scale annular reactor. Temperature programmed oxidation (TPO) experiments were also carried out to investigate the oxygen release/uptake of the catalyst materials. Palladium showed an unstable behavior both in the pilot and lab-scale experiments at temperatures well below the PdO to Pd transformation. An addition of Pt to Pd stabilized, and in some cases increased, the catalytic activity for methane combustion. The TPO experiments showed that the oxygen release peak was shifted to lower temperatures even for low additions of Pt, i.e. Pd:Pt = 2:1. For additions of rhodium only small beneficial effects were seen. The steady-state behavior of the lab-scale annular reactor correspond well to the pressurized pilot-scale tests.