Fluidized‐Bed Membrane Reactors

Abstract

168 Fluidized-Bed Membrane Reactorsin the fl uidized bed. The product selectivity and yield were increased in part of the operation range. A signifi cant infl uence of the secondary gas injections was approved.A concept for separate reactant dosing was proven by Soler et al. ( 1999 ) for the oxidative dehydrogenation of n -butane to butadiene by separation of the oxidation and the reduction zones in the same catalytic fl uidized bed. The butadiene yield was about 200% higher than in the conventional reactor.Al -Sherehy, Grace, and Adris ( 2005 ) investigated the effect of the discrete distributing gaseous feed along a bubbling fl uidized bed on the ethane partial oxidation to ethylene and acetic acid. An improvement of the product selectivity and the reactor performance was achieved by using multiple nozzles for the secondary gas injection.Recent developments in the material sciences, and especially the development of suitable inorganic membranes which are chemically resistant and stable at high temperatures, offer the integration of membranes into catalytic reactors and a new reactor design. Only a limited number of applications of the membrane -assisted FLBR for the distributive feeding of one of the reactants have been investigated and most of these applications involve the controlled dosing of reactant via porous membranes. Alonso et al. ( 2001 ) studied the butane partial oxidation in an externally FLBMR. Air from a pre -heated fl uidized bed (catalytic inert) fl ows across a catalyst -fi lled membrane tube. A detailed reactor model demonstrated a minimized hot spot effect and maleic anhydride yields were predicted to be 50% higher compared to a conventional fi xed -bed reactor. However, later experimental data (Alonso et al. , 2005 ) show that, on average, the overall performance in the conventional fi xed bed is superior to the membrane confi guration because selectivity is higher and the reactor may be operated at higher temperatures resulting in superior MA yields. Ramos et al. (2001) proposed a similar concept for the partial oxidation of propane to propene. Air fl uidized the shell side where catalyst -fi lled membrane tubes and cooling coils were immersed. Oxygen transport through the membrane was controlled by the pressure drop. The controlled oxygen addition along the axis improved the propene selectivity and broadened the operating range with respect to the hydrocarbon and oxygen feed rates. Recently, Deshmukh et al. ( 2005a, 2005b ) constructed a small laboratory -scale FLBMR for the partial oxidation of methanol to formaldehyde. High methanol conversion and high selectivity to formaldehyde were achieved with safe reactor operation (isothermal reactor conditions) at higher methanol inlet concentrations than that currently employed in industrial processes.An area of much current interest is the production of hydrogen via methane steam reforming or autothermal reforming. Fluidized -bed concepts were proposed to solve the problems of thermal control encountered in fi xed -bed reactors. These studies...

Maleic anhydride production in a cross‐flow reactor: A comparative study

“…Nevertheless, later experimental work carried out by the authors [9] failed to prove the theoretical findings, this was attributed to limitations in heat transfer due to the flow across the membrane. On the other hand, the experimental work presented by Tóta et al [36] proved that utilising membrane reactors improves the yield of ethane oxidation by about 8%, compared to PBRs. Moreover, the simulation results presented by the authors agree qualitatively with the corresponding experimental findings.…”

Comparative analysis of the functional results of tongue reconstruction with four kinds of free flaps after radical resection of tongue cancer

“…Tongue cancer is the most common malignant tumor of oral cancer. The incidence of tongue cancer has increased in the past 30 years [1,2]. Surgical resection is an essential strategy for the treatment of tongue cancer.…”