scholarly journals Evaluation of a Ti–Base Alloy as Steam Cracking Reactor Material

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2550 ◽  
Author(s):  
Stamatis A. Sarris ◽  
Kim Verbeken ◽  
Marie-Françoise Reyniers ◽  
Kevin M. Van Geem
Keyword(s):  
Base Alloy ◽  
Coke Formation ◽  
Surface Oxidation ◽  
Reactor Material ◽  
X Ray ◽  
Stirred Reactor ◽  
Initiation And Propagation ◽  
Steam Cracking ◽  
Temperature Pretreatment ◽  
Temperature Scanning

Low-coking reactor material technologies are key for improving the performance and sustainability of steam crackers. In an attempt to appraise the coking performance of an alternative Ti–base alloy during ethane steam cracking, an experimental study was performed in a jet stirred reactor under industrially relevant conditions using thermogravimetry (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, and dilution δ = 0.33 kgH2O/kgHC). Initially, a typical pretreatment used for Fe–Ni–Cr alloys was utilized and compared with a pretreatment at increased temperature, aiming at better surface oxidation and thus suppressing coke formation. The results revealed a decrease in coking rates upon high temperature pretreatment of the Ti–base alloy, however, its coking performance was significantly worse compared to the typically used Fe–Ni–Cr alloys, and carbon oxides formation increased by a factor of 30 or more. Moreover, the analyzed coupons showed crack propagation after coking/decoking and cooling down to ambient temperature. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy indicated that the prompt and unsystematic oxidation of the surface and bulk caused observable crack initiation and propagation due to alloy brittleness. Hence, the tested Ti–base alloy cannot be considered an industrially noteworthy steam cracking reactor alloy.

scholarly journals Alumina-based Coating for Coke Reduction in Steam Crackers

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2025
Author(s):  
Stamatis A. Sarris ◽  
Steffen H. Symoens ◽  
Natalia Olahova ◽  
Marie-Françoise Reyniers ◽  
Guy B. Marin ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Base Alloy ◽  
Product Distribution ◽  
X Ray ◽  
Barrier Coating ◽  
Sulfur Addition ◽  
Steam Cracking ◽  
On Line ◽  
Set Up ◽  
Section Analysis

Alumina-based coatings have been claimed as being an advantageous modification in industrial ethylene furnaces. In this work, on-line experimentally measured coking rates of a commercial coating (CoatAlloy™) have pointed out its superiority compared to an uncoated reference material in an electrobalance set-up. Additionally, the effects of presulfiding with 500 ppmw DMDS per H2O, continuous addition of 41 ppmw S per HC of DMDS, and a combination thereof were evaluated during ethane steam cracking under industrially relevant conditions (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, dilution δ = 0.33 kgH2O/kgHC). The examined samples were further evaluated using online thermogravimetry, scanning electron microscopy and energy diffractive X-ray for surface and cross-section analysis together with X-ray photoelectron spectroscopy and wavelength-dispersive X-ray spectroscopy for surface analysis. The passivating coating illustrated a better performance than the reference Ni-Cr Fe-base alloy after application of an improved pretreatment, followed by piddling changes on the product distribution. Presulfiding of the coating affected negatively the observed coking rates in comparison with the reference alloy, so alternative presulfiding and sulfur addition strategies are recommended when using this barrier coating.

Influence of the Reactor Material Composition on Coke Formation during Ethane Steam Cracking

2014 ◽  
Vol 53 (15) ◽  
pp. 6358-6371 ◽  
Author(s):  
Andrés E. Muñoz Gandarillas ◽  
Kevin M. Van Geem ◽  
Marie-Françoise Reyniers ◽  
Guy B. Marin
Keyword(s):  
Coke Formation ◽  
Material Composition ◽  
Reactor Material ◽  
Steam Cracking

Coke Formation Reduction in the Steam Cracking of Naphtha on Industrial Alloy Steels Using Sulfur-Based Inhibitors

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Darioush Salari ◽  
Aligholi Niaei ◽  
Mohammad Reza Shoja ◽  
Reza Nabavi
Keyword(s):  
Coke Formation ◽  
Dimethyl Disulfide ◽  
Coke Deposition ◽  
X Ray ◽  
Industrial Alloy ◽  
Stainless Steel 304 ◽  
Steam Cracking ◽  
Alloy Steels ◽  
Cylindrical Reactor ◽  
Scanning Electron

Coke formation reduction during naphtha pyrolysis was investigated using dimethyl disulfide (DMDS) and carbon disulfide (CS2) as inhibitors with different feed stocks. Different industrial nickel alloy steels such as stainless steel 304 and 316 (SS304, SS316), HP-modified (HP-mod) and HP-micro (HP-mic) were used as coupons in a quartz cylindrical reactor for coke formation studies. Coke formation significantly reduced in the presence of the additives or using feeds with more sulfur compounds. It was revealed that HP-mic alloy has the least coke deposition rate between other alloys. Scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDAX) were used for morphological and elemental surface analyses, respectively. It was found that cokes formed in presence of sulfurous inhibitors are softer and have less metal concentrations.

scholarly journals Effect of Phosphine on Coke Formation during Steam Cracking of Propane

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5075
Author(s):  
Manjunath Patil ◽  
Marko Djokic ◽  
Kim Verbeken ◽  
Marie-Francoise Reyniers ◽  
Kevin Van Geem
Keyword(s):  
Flow Reactor ◽  
Positive Impact ◽  
Coke Formation ◽  
Plug Flow ◽  
X Ray ◽  
High Temperature Alloys ◽  
Steam Cracking ◽  
Reactor Materials ◽  
Line Scanning

In conventional steam cracking feedstocks, contaminants such as sulfur, phosphine, and heavy metal components, present in trace levels, are believed to affect coke formation on high temperature alloys. To gain an understanding of the role of phosphine coking rates on 25/35, CrNi and Al-containing reactor materials were determined in a plug flow reactor during cracking of a propane feedstock doped with ppb levels of PH3 in the presence of DMDS. The presence of phosphine decreased the asymptotic coking rates by more than 20%, while it had a smaller influence on the catalytic coking rate. The coking rate was more severely reduced for the 25/35 CrNi alloy in comparison to the Al-containing alloy. The ppm levels of phosphine did not affect the olefin yields nor the production of undesired carbon monoxide. The morphology of the coked alloys were studied using an off-line Scanning Electron Microscope with Energy Dispersive X-ray detector (SEM with EDX) images of coked coupons. Two types of coke morphology are observed, i.e., filamentous coke with DMDS as an additive and globular coke in the presence of phosphine. The effect of phosphine on the material has a positive impact on the oxide scale homogeneity of 25/35 CrNi alloy, whereas the Al-containing alloy remained unchanged.

scholarly journals Non-Thermal Plasma-Modified Ru-Sn-Ti Catalyst for Chlorinated Volatile Organic Compound Degradation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Yujie Fu ◽  
You Zhang ◽  
Qi Xin ◽  
Zhong Zheng ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Surface Oxidation ◽  
Treatment Method ◽  
X Ray ◽  
Chlorinated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Doped Titania

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities.

scholarly journals Mapping the coke formation within a zeolite catalyst extrudate in space and time by operando computed X-ray diffraction tomography

2021 ◽  
Author(s):  
David S. Wragg ◽  
Georgios N. Kalantzopoulos ◽  
Dimitrios K. Pappas ◽  
Irene Pinilla-Herrero ◽  
Daniel Rojo-Gama ◽  
...  
Keyword(s):  
Zeolite Catalyst ◽  
Coke Formation ◽  
Diffraction Tomography ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space And Time

scholarly journals Efficiency of using heteropoly compounds of the type (NH4)2[Co(H2O)4]2[Mo8O27]∙6H2O as catalysts for the production of ethylene

2019 ◽  
Vol 60 (11) ◽  
pp. 85-92
Author(s):  
Nikita A. Panurin ◽  
◽  
Natalya Yu. Isaeva ◽  
Ekaterina B. Markova ◽  
Tatiana F. Sheshko ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Fluorescence Analysis ◽  
Heteropoly Compound ◽  
Cascade Reactions ◽  
Environmental Benefits ◽  
Heteropoly Compounds ◽  
X Ray ◽  
Cell Parameters

Carrying out heterogeneous acid catalysis with the use of heteropoly compounds has received considerable attention due to the great economic and environmental benefits. In spite of this, its industrial application is limited as there are difficulties in catalyst regeneration (settling) caused by its relatively low thermal stability. The aim of present work was to search and select catalysts related to the class of heteropoly compounds for propane cracking, to test the selectivity of the prosses as well as to discuss possible approaches for solving the problem of catalyst deactivation, that can contribute to achieve stable characteristics of solid heteropoly catalysts. Among these approaches are: the development of new catalysts with high thermal stability, the modification of catalysts to promote coke combustion, the inhibition of coke formation on heteropoly compound catalysts during the process, carrying out the reactions in supercritical media and also the cascade reactions using a multifunctional heteropoly catalyst. The obtained catalyst was also studied by physicochemical methods to get deep knowledge about which features of these compounds influence on the catalytic activity. A highly active and selective catalyst for ammonium octomolybdenocobaltate(II) ammonium (NH4)2[Co(H2O)4]2[Mo8O27]∙6H2O was synthesized for cracking associated petroleum gases. The qualitative, quantitative, and structural composition as well as the specific surface area of the obtained catalyst was established by the methods of X-ray diffraction, X-ray phase and fluorescence analysis. It was revealed that ammonium octomolybdenocobaltate(II) crystallizes in a triclinic syngony with cell parameters: а = 8.6292(9) Å b = 9.4795(10) Å c = 12.2071(13) Å α = 104.326(2)° β = 109.910(2)° γ = 100.820(2)°.

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