Butene partial oxidation

Small olefins, notably ethylene (ethene), propene, and butene, form the building blocks of the petrochemical industry. These molecules originate among others from the FCC process, but they are also manufactured by the steam cracking of naphtha. A wealth of reactions is based on olefins. As examples, we discuss here the epoxida-tion of ethylene and the partial oxidation of propylene, as well as the polymerization of ethylene and propylene. 

Numerous chemical intermediates are oxygen rich. Methanol, acetic acid and ethylene glycol show a O/C atomic ratio of 1, as does biomass. Other major chemicals intermediates show a lower O/C ratio, typically between 1/3 and 2/3. This holds for instance for propene and butene glycols, ethanol, (meth)acrylic acids, adipic acid and many others. The presence of some oxygen atoms is required to confer the desired physical and chemicals properties to the product. Selective and partial deoxygenation of biomass may represent an attractive and competitive route compared with the selective and partial oxidation of hydrocarbon feedstock. 

Many substances can be partially oxidized by oxygen if selective catalysts are used. In such a way, oxygen can be introduced in hydrocarbons such as olefins and aromatics to synthesize aldehydes (e.g. acrolein and benzaldehyde) and acids (e.g. acrylic acid, phthalic acid anhydride). A selective oxidation can also result in a dehydrogenation (butene - butadiene) or a dealkylation (toluene -> benzene). Other molecules can also be selectively attacked by oxygen. Methanol is oxidized to formaldehyde and ammonia to nitrogen oxides. Olefins and aromatics can be oxidized with oxygen together with ammonia to nitriles (ammoxidation). 

Under similar conditions, the photocatalytic oxidation of 2-or 3-methyl-l-butene and of 2-methyl-2-butene over Ti(>2 yielded carbonyl compounds as partial oxidation products (18). However, the selectivity to a particular aldehyde or ketone was reduced by cleavages not only of the double bond but also of the Cg-Cy bond. 

The partial oxidation of olefins over a variety of mixed oxide catalysts is well known [ I ] and has been studied in great detail. For example, iron antimony oxide is known to be a selective catalyst for the partial oxidation of propene yielding acrolein [2-4] and of 1-butene yielding 1,3 butadiene and 2-butenal [5,6], The oxidation of paraffins, like propane, with this type of catalysts yields only the combustion products CO and CO2 [7]. Propane can however be selectively oxidised over this type of catalysts in the presence of ammonia to yield acrylonitrile [8],... 

It was established that ethene oxide, CO and CO2 were formed on Ag-Sup at temperature range of 370-410 K. Such the products were formed at the presence of Ag-Im2, although the reaction took place at more high temperatures (450-500 K). The major product of partial oxidation on Ag-Ph was butene-2,3 oxide. It has been formed begining from 340 K with 100 % selectivity and ethene conversion being of 30-35 % at 408-415 K. The ethene oxide was detected in trace amounts. 

Vanadium pentoxide catalytic membrane reactor for partial oxidation of 1-butene... 

The vanadium pentoxide cataKtic membrane reactor was prepared by coating its sol inside the Vycor tube membrane. After heat treatment of the prepared membrane, the [010] planes of vanadium pentoxide layer were grown largely which contributes to partial oxidation reaction of 1-butene to maleic anhydride. The partial oxidation of 1-butene to maleic anhydride was carried out in the catalytic membrane reactor. The maximum selectivity of 95% was obtained at 350 °C when the surface velocity was 500cm/h. And at this condition, oxygen permeability was almost four times higher than the reaction had not occured. 

One of the most industrially important reactions using vanadium pentoxide(V205) catalyst is the partial oxidation of 1-butene to maleic anhydride [1]. Partial oxidation reactions are inherently unselective and often make by-products of little or no value. Oxygen-rich feeds result in low product selectivities and high hydrocarbon conversions [2]. Because partial oxidation and total oxidation always proceed competitively, the selectivity of maleic anhydride from 1-butene is low. Though fixed bed reactors or fludized bed reactors have been used for partial oxidation for the past 30 years, the selectivity of maleic anhydride has not been obtained higher than 69% [3]. Some attempts have been reported on a new type of reactor to overcome the above limit. This is a membrane reactor which offers some advantages. A membrane reactor plays a... 

The V206-coated catalytic membrane was applied to the partial oxidation reaction to produce maleic anhydride from 1-butene. The maximum selectivity was 95% at 350 °C and the permeability of oxygen through the V20s-coated catalytic membrane was enhanced. More careful studies are needed about this permeability enhancement. 

Butene oligomerization, phenol synthesis from benzene, butane partial oxidation, and other reactions carried out in membrane reactors... 

By far the most reports deal with the partial reduction of ZnO, used as support, and subsequent formation of Zn-containing intermetallic compovmds. In the case of Pd/ZnO, a catalyst used for the decomposition (83), the partial oxidation (84-89) and the steam reforming of methanol (90-94), the interaction between the supported Pd particles and the partial reduced support can lead to a mixture of ZnPd, ZnsPd2, and ZnPd2. When this catalyst is used for the hydrogenation of unsaturated hydrocarbons, such as butenes, isoprene, or crotonaldehyde, only the formation of ZnPd is observed (95-97). The same holds for reductive treatments of Pd/ZnO at temperatures above 400°C (Fig. 4). The supported catalyst Pd/ZnO is not the usual case, since normally a mixture of intermetallic compovmds and the originally supported transition metal is observed. 

Investigation of pyrolysis of the butenes was chosen here as a complement to previous work in this laboratory on pyrolysis and partial oxidation of n-butane (1)(2)(3). Previous investigations of butene pyrolysis typically have employed static systems and/or high conversions (4)(5)(6)(7)(8)(9). 

---