Search Results

You are looking at 1 - 10 of 28 items for :

  • "Coke formation" x
  • Refine by Access: All Content x
Clear All

, endothermic and accompanied by volume expansion. Therefore, higher temperatures and lower pressures shift it to completion. Higher temperatures, on the other hand, promote side reactions, coke formation, and catalyst deactivation. Catalytic PDH has been

Restricted access

indicates a rapid coke formation, which takes place on acid sites catalyzing the reaction. Similarly, in the present reaction, the decrease in percentage conversion with reaction time may also be due to the blocking of the acid sites by the coke formed

Restricted access

abundant acid sites, especially the strong acid sites, the olefins will move to the acid sites to induce the side reactions and finally the formation of coke, and coke formation is an important factor of catalyst deactivation for the process of alkane

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Marcelo Mendes Viana, Maura Berger Maltez Melchert, Leandro Cardoso de Morais, Pedro Maurício Buchler, and Jo Dweck

part occurs, and inorganic oxides remain. To better understand how coke formation occurs, several temperatures were used to determine the residual mass in nitrogen and air atmospheres to estimate, by their difference, the amount of coke formed

Restricted access
Reaction Kinetics, Mechanisms and Catalysis
Authors: Viorel Chihaia, Karl Sohlberg, Monica Dan, Maria Mihet, Alexandru R. Biris, Petru Marginean, Valer Almasan, George Borodi, Fumiya Watanabe, Alexandru S. Biris, and Mihaela D. Lazar

reformers in which: (i) Au or Ag is added to the metal and (ii) the support is promoted with La 2 O 3 or CeO 2 . The addition of Au and Ag was reported to reduce the coke formation on the nickel catalysts during hydrocarbon reforming reactions, reducing the

Restricted access

Abstract  

This work evaluates the effect of the FCC catalyst components—Y zeolite, kaolin and alumina—on the formation of coke during the cracking of heavy residue (HR) of petroleum. The Y zeolite, kaolin and alumina were mixed with a HR at a ratio of approximately 1:4. The effect was studied using dynamic thermogravimetry at a heating rate of 50 K min−1, with N2 (between 35 and 700 °C) and air (in the 700–1,000 °C temperature range). The HR analyzed in these conditions formed 8.1% of coke. All the mixtures presented larger coke formation than that observed in pure HR. The Y zeolite presented fourfold larger coke formation, while kaolin and alumina showed twofold higher formation than pure HR. The major focus of this study was to verify the sensitivity of the TG technique in providing information about coke formation in the fluid catalytic process of refineries.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: P. Gronchi, D. Fumagalli, R. Del Rosso, and P. Centola

Coke formation in the dry reforming of methane was studied using a thermobalance (TG) and with a catalytic microreactor in the temperature range 800–950 K. Silica-supported and lanthana-supported nickel catalysts were examined. The effects of process variables such as temperature and gas composition (He dilution, CH4/CO2 ratio) on the coke formation rate were determined. The reactivity of H2 on several kinds of carbon was also investigated. The morphology of the coke was studied by scanning electron microscopy (SEM). The induction times for coke formation were significantly affected by temperature and by the CO content in the feed gas. The results of catalytic tests were consistent with the TG measurements. The behaviour of SiO2 and La2O3 supported Ni catalysts agree with a mechanism in which the lanthana support plays an important role in the carbon deposition.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Maria Luisa A. Gonçalves, D. A. Ribeiro, Deusa Angélica P. Da Mota, Ana Maria R. F. Teixeira, and M. A. G. Teixeira

Summary Thermogravimetry (TG) was applied to evaluate the thermal behavior of five refinery atmospheric distillation residues (ATR) obtained from different Brazilian crude oils. The asphaltenes were extracted of each sample and their influence on coke formation was studied. It was observed that they have a great contribution on carbonaceous residues formation during pyrolysis and that the heavier the ATR sample, the higher is the contribution of other heavy components present in ATR samples.

Restricted access

A method for comparing the thermochemical properties of high- boiling fractions and residues has been developed. The thermal effects vary in intensity and range, depending on the fractional and structure group compositions of the studied samples. Good agreement between DTA and TG data is observed. The thermal analysis of samples, obtained by liquid adsorption chromatography, reveals the specific differences of the individual structure group fractions in the processes of evaporation, thermal decomposition and coke formation. The observed effects are interpreted from the point of view of the different thermal stabilities and reactivities of the compounds contained in the Chromatographic fractions. The results show that the TG-DTA method allows the quick determination of some characteristics depending on the group compositions of the high-boiling fractions and residues from West Siberian crude oiL.

Restricted access

are formed only from EtOH/H 2 O. Table 1 Outlet selectivity to the typical by-products at t = 30′ and coke formation speed

Restricted access