Thermal noncatalytic

Essentially the same triple peak system also appeared with Pt-black, but the entire spectrum was shifted toward lower temperatures (r ,a,j = 155°, 175°, and 195°C, respectively). 7>a s-hexatriene gave the same spectrum, but with cw-triene a fourth, low-temperature peak appeared at 140°C. This should correspond to the facile cyclization of cij-triene. The fact that a peak of similar appears when benzene is desorbed from the catalyst is another strong argument against the purely thermal (noncatalytic) character of cyclization of c/s-l,3,5-hexatriene. 

Hi-Chloroff A thermal (noncatalytic) process for removing chlorine from chlorinated hydrocarbon wastes containing either low or high concentrations of chlorine. Developed by Kinetics Technology International. See also Chloroff. 

Because of inorganic components in waste plastics, thermal, noncatalytic processes present some advantages. In order to obtain high conversion Chinese inventors [52] propose a two-step process thermal cracking in the first step in order to obtain partial cracking of waste plastics and to separate inorganic components, and in the next step catalytic cracking of the product over a fixed-bed catalyst. 

Lubricating oil. A new process has been developed for the conversion of waste plastic and Fischer-Tropsch (FT) wax to lube range molecules that can be hydroisomerized to low pour point lube base oils of unconventional base oil (UCBO) quality. The process employs pyrolysis, a thermal, noncatalytic, low-pressure reaction where high-molecular-weight molecules are cracked to ones of lower molecular weight. The major by-product is diesel, with little production of C4- gas. The by-product liquids are highly olefinic and could be oligomerized to provide additional base oil. 

Visbreaking is a relatively mild thermal (noncatalytic) cracking process that is used to reduce the viscosity of residua. A visbreaker reactor may be similar to a delayed coker with a furnace tube followed by a soaker drum. However, the drum is much smaller in volume to limit the residence time with the entire liquid product flowing overhead. Alternatively, the entire visbreaker may be a long tube coiled within a furnace. Coke formation can occur and the coke accumulates on visbreaker walls periodic decoking (cleaning) is necessary. 

It has been mentioned that gaseous reactions are more suitably carried out on a commercial scale in flow equipment than in batch reactors. Consider the following example. Watson has studied the thermal (noncatalytic) cracking of... 

A mixture of butenes and steam is to be thermally (noncatalytically) cracked in a tubular-flow reactor at a constant temperature of 1200°F and a constant pressure of 1.0 atm. Although the feed consists of a number of different butenes and the products vary from coke to butadiene, the rate of reaction may be adequately represented by the first-order mechanism... 

Demonstrate the feasibility of the superadiabatic partial oxidation concept as a basis for developing an innovative process for production of economically viable quantities of hydrogen through the thermal, noncatalytic decomposition of hydrogen sulfide (H2S) in H2S-rich waste streams into hydrogen and elemental sulfur, without the input of additional energy (and no additional carbon dioxide [CO2] emissions). 

Boukherroub R, Morin S, Wayner DDM, Bensebaa F, Sproule Gl, Baribeau JM, Lockwood DJ (2001) Ideal passivation of luminescent porous silicon by thermal, noncatalytic reaction with alkenes and aldehydes. Chem Mater 13 2002-2011 Boukherroub R, Wojtyk JTC, Wayner DDM, Lockwood DJ (2002) Thermal hydrosilylation of undecylenic acid with porous silicon. J Electrochem Soc 149 59-63 Boukherroub R, Petit A, Loupy A, Chazalviel JN, Ozanam F (2003) Microwave-assisted chemical functionalization of hydrogen-terminated porous silicon surfaces. J Phys Chem B 107 13459-13462... 

Boukherroub R, Morin S, Wayner DDM, Bensebaa F, Sproule Gl, Baribeau JM, Lockwood DJ (2001) Ideal passivation of luminescent porous silicon by thermal, noncatalytic reaction with alkenes and aldehydes. Chem Mater 13 2002-2011... 

SCHEME 1.94 Synthesis of O-vinyl oximes and pyrroles from 4,4 -diacetyldiphenyl sulfide dioxime and acetylene in the system LiOH/DMSO. Thermal (noncatalytic) rearrangement of O-vinyl oximes to pyrroles. 

Compared with catalytic HDS in which higher sulfur removal is expected when the pressure is increased, for NHDS (thermal, noncatalytic), the sulfur removal is governed by free radical mechanism, and the presence of hydrogen may quench the free radicals involved during sulfur removal. The heavier and more reactive feeds (those that generate higher number of free radicals) are more sensitive to the increase in reaction pressure as that causes saturation of free radicals (Sanford, 1994). 

Another hydrogenation process utilizes internally generated hydrogen for hydroconversion in a single-stage, noncatalytic, fluidized-bed reactor (41). Biomass is converted in the reactor, which is operated at about 2.1 kPa, 800°C, and residence times of a few minutes with steam-oxygen injection. About 95% carbon conversion is anticipated to produce a medium heat value (MHV) gas which is subjected to the shift reaction, scmbbing, and methanation to form SNG. The cold gas thermal efficiencies are estimated to be about 60%. 

Extrusion Resins. Extmsion of VDC—VC copolymers is the main fabrication technique for filaments, films, rods, and tubing or pipe, and involves the same concerns for thermal degradation, streamlined flow, and noncatalytic materials of constmction as described for injection-molding resins (84,122). The plastic leaves the extmsion die in a completely amorphous condition and is maintained in this state by quenching in a water bath to about 10°C, thereby inhibiting recrystallization. In this state, the plastic is soft, weak, and pHable. If it is allowed to remain at room temperature, it hardens gradually and recrystallizes partially at a slow rate with a random crystal arrangement. Heat treatment can be used to recrystallize at controlled rates. 

FLUID COKING A noncatalytic, thermal process for converting bitumen and coal liquids to lighter hydrocarbon fluids and gases. Developed by the Exxon Research Engineering Company and used commercially since 1954. See also FLEXICOKING. 

Visbreaking A thermal cracking process which reduces the viscosity of the residues from petroleum distillation, so that they may be handled at lower temperatures. It is essentially a high-temperature, noncatalytic pyrolytic process conducted in the presence of steam. See also HSC. 

Although the noncatalytic thermal disproportionation of alkenes is symmetry-for-bidden, the formation of metal complex 1 with the four-centered cyclic intermediate makes the reaction symmetry-allowed.61... 

The extent of the hydrocracking is, like the hydrodesulfurization reaction, dependent upon the temperature, and both reaction rates increase with increase in temperature. However, the rate of hydrocracking tends to show more marked increases with temperature than the rate of hydrodesulfurization. The overall effect of the increase in the rate of the hydrocracking reaction is to increase the rate of carbon deposition on the catalyst. This adversely affects the rate of hydro-desulfurization hydrocracking reactions are not usually affected by carbon deposition on the catalyst since they are more dependent upon the noncatalytic scission of covalent bonds brought about by the applied thermal energy. 

The feedstock, mixed with recycle stock from the fractionator, is injected into the cracker is immediately absorbed into the pores of the particles by capillary force and is subjected to thermal cracking (Figure 8-7). In consequence, the surface of the noncatalytic particles is kept dry and good fluidity is maintained allowing a good yield of, and selectivity for, middle distillate products (Table 8-3). Hydrogen-containing gas from the fractionator is used for the fluidization in the cracker. 

Thermal coke the carbonaceous residue formed as a result of a noncatalytic thermal process the Conradson carbon residue the Ramsbottom carbon residue. 

Thermally induced deactivation of catalysts is a particularly difficult problem in high-temperature catalytic reactions. Thermal deactivation may result from one or a combination of the following (i) loss of catalytic surface area due to crystallite growth of the catalytic phase, (ii) loss of support area due to support collapse, (iii) reactions/transformations of catalytic phases to noncatalytic phases, and/or (iv) loss of active material by vaporization or volatilization. The first two processes are typically referred to as "sintering." Sintering, solid-state reactions, and vaporization processes generally take place at high reaction temperatures (e.g. > 500°C), and their rates depend upon temperature, reaction atmosphere, and catalyst formulation. While one of these processes may dominate under specific conditions in specified catalyst systems, more often than not, they occur simultaneously and are coupled processes. 

---