Hydrogenation noncatalytic

Noncatalytic hydrogenation is promising from a commercial point of view if the side reactions during the process can be carefully excluded. Moreover, this is of particular importance for online reduction of NBR emulsion. 

Figure 2. Noncatalytic hydrogenation—product yields vs. vitrinite + exinite content. Curve a, total conversion (X) Curve b, extract ( ) (10). (Note Lines a and b relate to coals where the mean maximum reflectance (R0 max) of the vitrinite fall in the range 0.43-0.68%. Values in parenthesis refer to R0 max for...

Dynaphen A process for converting mixed alkyl phenols (from coal liquids or lignin) to benzene, phenol, and fuel gas, by noncatalytic hydrogenation at high temperature. Developed and offered by Hydrocaibon Research. 

Noncatalytic hydrogenation of olefins under the conditions of hydropyrolysis is a definite possibility. Such a reaction could proceed by a chain mechanism involving addition of a hydrogen atom to a double bond, followed by metathesis between the radical produced and molecular hydrogen ... 

Ionic hydrogenation. Noncatalytic hydrogenation of C=C, C = 0, C=N, C—OH, C—X groups can be effected with this combination. The acid supplies a proton and the silane a hydride ion ... 

Oelert, H. H. Integrated Two-Stage Noncatalytic Hydrogenative Upgrading of Petroleum Residue (1) Reactions and Product Distribution Erdol, Erdgas, Kohle 103 (1987) p. 437-440. 

The clean coke process (Figure 19.6) involves feeding oxidized clean coal into a fluidized bed reactor at temperatures up to 800°C (1470°F) whereupon the coal reacts to produce tar, gas, and low-sulfur char. Alternatively, the coal may be processed by noncatalytic hydrogenation at455°C-480°C (850°F-900°F) and pressures of up to 5000 psi hydrogen. 

Fixed-bed noncatalytic reactors. Fixed-bed reactors can be used to react a gas and a solid. For example, hydrogen sulfide can be removed from fuel gases by reaction with ferric oxide ... 

The earliest examples of analytical methods based on chemical kinetics, which date from the late nineteenth century, took advantage of the catalytic activity of enzymes. Typically, the enzyme was added to a solution containing a suitable substrate, and the reaction between the two was monitored for a fixed time. The enzyme s activity was determined by measuring the amount of substrate that had reacted. Enzymes also were used in procedures for the quantitative analysis of hydrogen peroxide and carbohydrates. The application of catalytic reactions continued in the first half of the twentieth century, and developments included the use of nonenzymatic catalysts, noncatalytic reactions, and differences in reaction rates when analyzing samples with several analytes. 

Pyrolysis of chlorodifluoromethane is a noncatalytic gas-phase reaction carried out in a flow reactor at atmospheric or sub atmospheric pressure yields can be as high as 95% at 590—900°C. The economics of monomer production is highly dependent on the yields of this process. A significant amount of hydrogen chloride waste product is generated during the formation of the carbon—fluorine bonds. 

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%. 

In general, hydroboration—protonolysis is a stereoselective noncatalytic method of cis-hydrogenation providing access to alkanes, alkenes, dienes, and enynes from olefinic and acetylenic precursors (108,212). Procedures for the protonolysis of alkenylboranes containing acid-sensitive functional groups under neutral or basic conditions have been developed (213,214). 

Isopropyl alcohol can be partially oxidized by a noncatalytic, liquid-phase process at low temperatures and pressure to produce hydrogen peroxide [7722-84-1] and acetone (24—26). 

The Claus process converts hydrogen sulfide to elemental sulfur via a two-step reaction. The first step involves controUed combustion of the feed gas to convert approximately one-third of the hydrogen sulfide to sulfur dioxide (eq. 9) and noncatalytic reaction of unbumed hydrogen sulfide with sulfur dioxide (eq. 10). In the second step, the Claus reaction, the hydrogen sulfide and sulfur dioxide react over a catalyst to produce sulfur and water (eq. 10). The principal reactions are as foUow ... 

Electroless reactions must be autocatalytic. Some metals are autocatalytic, such as iron, in electroless nickel. The initial deposition site on other surfaces serves as a catalyst, usually palladium on noncatalytic metals or a palladium—tin mixture on dielectrics, which is a good hydrogenation catalyst (20,21). The catalyst is quickly covered by a monolayer of electroless metal film which as a fresh, continuously renewed clean metal surface continues to function as a dehydrogenation catalyst. Silver is a borderline material, being so weakly catalytic that only very thin films form unless the surface is repeatedly cataly2ed newly developed baths are truly autocatalytic (22). In contrast, electroless copper is relatively easy to maintain in an active state commercial film thicknesses vary from <0.25 to 35 p.m or more. 

The noncatalytic oxidation of propane in the vapor phase is nonselec-tive and produces a mixture of oxygenated products. Oxidation at temperatures below 400°C produces a mixture of aldehydes (acetaldehyde and formaldehyde) and alcohols (methyl and ethyl alcohols). At higher temperatures, propylene and ethylene are obtained in addition to hydrogen peroxide. Due to the nonselectivity of this reaction, separation of the products is complex, and the process is not industrially attractive. 

The direct oxidation of propylene with oxygen is a noncatalytic reaction occurring at approximately 90-140°C and 15-20 atmospheres. In this reaction hydrogen peroxide is coproduced with acetone. At 15% isopropanol conversion, the approximate yield of acetone is 93% and that for H2O2 is 87% ... 

Figure 7. Dependence of yields of hydrogenation products on the atomic hydro-gen-to-carbon ratio (a) Australian coals—noncatalytic conditions (10) (b) Canadian coals—catalytic conditions.

Catalyzed114,115 and noncatalytic partial oxidation116 have also been studied for the purpose of hydrogen production from methanol. 

A hydrogen peroxide still is used to concentrate peroxide by removing water. The still is of high-purity aluminum, a material that is noncatalytic to the decomposition of peroxide vapor. The still is designed to produce 78% hydrogen peroxide. It will explode spontaneously at about 90%. Illustrate some recommended design features for this still. 

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