Chemie Ingenieur Technik (73) 6 I 2001 666 R e a c t i o n E n g i n e e r i n g By this reasoning, the integral characterization of the 250* behavior of material surfaces by kinetic investigations of selected reference reactions offers a solution of this problem. Kinetics of the Catalytic Reduction Normally, the catalytic coke formation (incl. the coke formation accompanying metal dusting) serves as reference reac- of 2,4-Dinitrotoluene with Carbon tion under the conditions of steam cracking (reactor and transfer- Monoxide and Water line exchanger (TLE) and the manufacturing/processing of CO/H syngases, respectively. J a n i n a I l m u r z y n s k a * Now, it is possible to simulate such reactions with well L e c h o s l a w K r o l i k o w s k i * * defined results in lab-scale apparatus. The experimental pyrolysis M a l g o r z a t a J a r o s z * set-up includes the coupling of an apparatus (radiation and TLE *Industrial Chemistry Research Institute, Rydygiera 8, 01-793 zone) with a thermobalance. This arrangement allows investiga- Warsaw, Poland tions of coking rates **Wroclaw University of Technology, Norwida 4/6, Wroclaw, Poland ± of commercial and surface pretreated alloys and ± of different feedstocks and additives (coke inhibitors) The kinetics of the production of 2,4-toluenediamine by means of as well as in radiation and TLE zone. reduction of 2,4-dinitrotoluene in the liquid phase using water ± gas In order to obtain reliable statements on the advantages shift reaction was studied over Pd/Fe/J catalyst system in the tem- 0 or disadvantages for the use of alloyed steels with coating layers or perature of 170 C at a pressure range between 2 and 8 MPa. Two otherwise surface pretreated/engineered steels comparative ex- different forms of the catalyst system were used: PdCl /FeCl /J 2 3 2, periments with the uncoated/untreated reference steel (blank where Pd and Fe were used as its chlorides, which undergone re- tests) or for the use of different feedstocks and additives is thought duction in the reaction conditions and (Pd, Fe)/C/J where Pd and to be advantageous for the planning of industrial employments. Fe were deposited on acetylene black. The reaction scheme has been proposed and Langmuir ± Hinshelwood ± type rate equation was used for both catalyst system forms. 252* 251* Copper ± Morphology and Selective Partial Oxidation Coke Formation ± A Measure for the H . - J . W o È l k Valuation of Alloys, Feedstocks and B . S t e i n h a u e r Additives at Thermal Reactions G . W e i n b e r g G . M e s t l W o l f g a n g Z y c h l i n s k i R . S c h l o È g l P e t e r H a r t i n g Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abt. Anorga- Institut fu È r Nichtklassische Chemie e.V. an der Universita È t Leipzig, nische Chemie, Faradayweg 4-6, D-14195 Berlin Permoserstr. 15, 04318 Leipzig, Germany Copper catalysts for selective partial oxidation reactions are of con- Industrially important carbon containing gas mixtures have to be siderable importance for industrial processes. Most important in produced at high temperatures in endothermic processes or trans- this context are the oxidation of glycol on copper metal and the ported at high temperatures. The metallic materials (steels) needed methanol synthesis on the system Cu-Al-Zn-O. Opposite to this for these purposes are not only exposed to temperature cycling importance, the fundamental redox behaviour of copper in the tem- stresses, but they often get also into contact both with reductive perature range between 25 C and 800 C is not precisely enough and oxidative gas phases. In practice, this leads to changes in known. Although investigated for a long time, it is still in the focus the mechanical stability and the chemical composition of the sur- studies . In this contribution, it is reported on a study of the re- face and subsurface layers and because of that to changes in the lation between oxygen-induced morphology changes and the cat- reactivity of the steel surfaces with respect to the gas phase spe- alytic activity of copper in model redox reactions, e.g. methanol cies. This results in an acceleration of the steel carburization, in oxidation and oxidative coupling of methane. an increasing formation of catalytic coke and subsequently in the undesired corrosion and/or erosion of the employed steels. The undesired changes can be proven by the use of spectroscopic, metallographic and partly by microscopic meth- ods. The data obtained in such ways refer to spot-checks on sur- face areas as a rule. Analytical descriptions of large surface areas are not possible. Therefore, the desired statements can normally only be made in a rough approximation. With these analytical data, however, it is not possible to predict the reactivity of surfaces characterized in such ways with regard to the reactive gas phase species.
Chemie-Ingenieur-Technik (Cit) – Wiley
Published: Jun 1, 2001