Monolith pitch

Figure 28.9. Epoxidation of ethylene calculated effect of the monolith pitch on C2H4 conversion, C2H4O selectivity and molar yield. Washcoat thickness 120 xm support volume fraction 0.2 ks 200 W/(m K) Tcool 250 C. Tube diameter 39.2 mm. Reprinted from Ref. 102. Copyright 2001 with permission from Elsevier.

Pitch. The principal outlet for coal-tar pitch is as the binder for the electrodes used in aluminum smelting. These are of two types. Older plants employ Sn derberg furnaces, which incorporate paste electrodes consisting of a mixture of about 70% graded petroleum coke or pitch coke and 30% of a medium-hard coke-oven pitch. This paste is added periodically to the top of the monolithic electrode as it is consumed. The more modem smelters employ prebaked electrodes requiring less binder, about 18%. 

A recently developed adsorbent version of ORNL s porous carbon fiber-carbon binder eomposite is named carbon fiber composite molecular sieve (CFCMS). The CFCMS monoliths were the product of a collaborative researeh program between ORNL and the University of Kentueky, Center for Applied Energy Researeh (UKCAER) [19-21]. The m.onoliths are manufactured in the manner deseribed in Section 2 from P200 isotropic pitch derived fibers. While development of these materials is in its early stages, a number of potential applieations can be identified. 

A wide variety of carbon materials has been used in this study, including multi-wall carbon nanotubes (sample MWNT) chemically activated multi-wall carbon nanotubes (sample A-MWNT)16, commercially available vapor grown carbon nanofibers (sample NF) sample NF after chemical activation with K.OH (sample A-NF) commercially pitch-based carbon fiber from Kureha Company (sample CF) commercially available activated carbons AX-21 from Anderson Carbon Co., Maxsorb from Kansai Coke and Chemicals and commercial activated carbon fibers from Osaka Gas Co. (A20) a series of activated carbons prepared from a Spanish anthracite (samples named K.UA) and Subituminous coal (Samples H) by chemical activation with KOH as described by D. Lozano-Castello et al.17 18 activated carbon monoliths (ACM) prepared from different starting powder activated carbons by using a proprietry polymeric binder from Waterlink Sutcliffe Carbons, following the experimental process described in the previous paper13. 

Melting of the carbon precursor a monolithic is heated with a pitch carbon, resulting in penetration of the carbon material into the pores of the monolith structure. During heating, carbonization occurs, solidifying the carbon on the monolith. 

The geometry of the internally finned monolith can be varied in a wide range. A number of possible geometric configurations are described in a patent on the application of the internally finned monolith as an element in a gas-liquid-solid reactor [9]. Geometric variables include channel size and shape, number of fins, fin height and thickness, channel array, pitch, and wail thickness. 

Figure 8 Cross sections of some internally finned monoliths with different channel shapes. A Circular channels B hexagonal channels C triangular channels D square channels. The line between the two arrows is the pitch p.

Two types of monolithic supports on the base of cordierite (Sbet =0,3 m /g, pitch 64 cell/cm ) and dense alumosilicate (Sbet = 0,6 m /g, pitch 16 cell/cm ) were used. 

Melting. A ceramic structure is heated with a pitch carbon in an inert atmosphere, resulting in melting of the pitch and penetration of the pores of the monolith structure with the carbonized pitch. 

Integral-type monolithic structures are produced by extrusion. The extrusion mixture generally includes the following components a type of carbon or carbon precursor such as activated carbon particles, graphite, carbon fibres, etc., a blinder such as phenol resin, hydroxylcellidose, coal tar pitch etc. and extrusion aids/plasticizers such as water or polymers. Typical preparation steps are mixing, extrusion, diying/solidification and carbonization. 

Alcaniz-Monge et prepared MSC from a low rank coal and a low cost binder, coal tar pitch. The bituminous coal was steam activated and then impregnated with a suitable solution of a coal tar pitch (coal/pitch ratio 60 40 by weight), then molded in a monolith form and carbonized at temperatures between 700°C to 1200°C. The monolith obtained was characterized by TGA, XRD, and SEM, and the porous structure was determined by adsorption of nitrogen at 77 K and COj at 273 K. The pitch acted as a binder and modified the porosity of the activated carbon, producing a material with molecular sieve properties. The pitch caused an efficient blockage of the pore entrances. The molecular properties were analyzed through the measurement of CH4 and CO2 adsorption kinetics (kinetic diameters 0.38 and 0.33 nm, respectively). 

Reactor diameter Reactor length Monolith void fraction Pitch... 

Figure 5 - Axial temperature profiles of the catalytic washcoat at the monolith centerline versus length of the monolith sections loaded in the reactor. Pitch 2.5 mm, other conditions as in Table 2.

FIG. 12—Anodic polarization diagrams of pitch-based graphite fiber (cross section exposed), monolithic 6061-T6 aluminum, and Gr(50 vol. %)/6061-T6 Al MMC plate exposed to deaerated 0.5 M Na2S04 at 30°C. Scan rate = 0.1 mV/s. A diagram for a composite consisting of 50 vol. % graphite and 6061-T6 aluminum was generated on the basis of the mixed-potential theory. 

Placed block revetments (or stone/block pitching) are a form of protection lying between revetments comprised of elements which are disconnected, such as rubble, and monolithic revetments, such as asphalt/concrete slabs. Individual elements of... 

Many improved designs of the top-shooter, side-shooter, and back-shooter types of thermal inkjet printheads have recently been proposed. Lee et al. [4] fabricated a monolithic thermal inkjet printhead, which enqtloyed the top-shooter firing mode as shown in Fig. 1. The heater had an area of 40 x 40 xm. The nozzles, with a diameter of 50 jxm, had a resolution of 300 dpi and a nozzle-to-nozzle pitch of 170 xm. Ink ejection up to the operating frequency of 11 kHz with an average ink dot diameter of about 110 xm was achieved under current pulses of 0.3 A and 5 xs. 

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