Acrolein from propylene

One of the more successful conversions has been the selective oxidation of propylene to acrolein. In 1948, Hearne and Adams (7) reported that cuprous oxide produced acrolein from propylene with a yield of about 50% at propylene/oxygen ratios of about one. Even though the yield of acrolein was low, the search for improved catalytic systems provided few catalysts until the development of catalysts based on bismuth and molybdenum. 

In 1959, Idol (2), and in 1962, Callahan et al. (2) reported that bismuth/molybdenum catalysts produced acrolein from propylene in higher yields than that obtained in the cuprous oxide system. The authors also found that the bismuth/molybdenum catalysts produced butadiene from butene and, probably more importantly, observed that a mixture of propylene, ammonia, and air yielded acrylonitrile. The bismuth/molybdenum catalysts now more commonly known as bismuth molybdate catalysts were brought to commercial realization by the Standard Oil of Ohio Company (SOHIO), and the vapor-phase oxidation and ammoxidation processes which they developed are now utilized worldwide. 

Oxidation of hydrocarbons in zeolites with blue light gives improved selectivity.442 Isobutane can be converted to tert-butylhydroperoxide with 98% selectivity. Benzalde-hyde is produced from toluene, acrolein from propylene, and acetone from propane. 

Weigert, W. M., Acrolein from propylene aided by new catalyst , Chan. Engng, 80 (15) 68-69 (1973). Schaai, G En Make acrolein from propylene . Hydrocarbon Processing, 52 (9) 218-220 (1973),... 

A major advantage of the riser reactor for catalytic cracking is that the gas and solid move in nearly plug flow, which gives more uniform catalytic activity and better selectivity than with a bubbling or turbulent fluidized bed. A riser reactor can be used for other rapid catalytic reactions, such as the production of acrolein from propylene [3] or the partial oxidation of n-butane to make maleic anhydride. In DuPont s butane oxidation process... 

Maleic anhydride from C4 to C6 fractions Acrolein from propylene process patent Acrolein from propylene... 

The first use of oxide oxidation catafysts for the production of acrolein from propylene with a cuprous oxide/silica formulation was described by Shell in 1948. This followed an Allied Chemical Company patent describing the potential production of aciylonitrile from propylene. As demand for these products increased during the 1950s, other, more efficient, catalysts based on mixed oxides were developed. The best early catalysts are listed in Table 4.13. 

Since aHyl chloride could be converted to glycerol by several routes, the synthesis of glycerol from propylene [115-07-1] became possible. Propylene can also be oxidized in high yields to acrolein [107-02-8]. Several routes for conversion of acrolein to glycerol are shown in Figure 1. 

In comparable reaction conditions as Pd +Cu +Y, Pd + and Cu2+ exchanged pentasil and ferrierite zeolites show a different type of activity [31]. The main products formed by propylene oxidation on these catalysts are acrolein and propionaldehyde below 120°C and 2-propanol above 120 C. Above 150°C consecutive oxidation of 2-propano1 to acetone is observed. The catalytic role of Pd and Cu in the 2-propanol synthesis is proposed to follow the Wacker concept. It is striking that when Pd + and Cu2+ are exchanged in 10-membered ring zeolites, oxidation of a primary carbon atoms seems possible, as acrolein and propionaldehyde are obtained from propylene. 

ACRYLIC ACID AND DERIVATIVES. [CAS 79-10-7]. Acrylic acid (propenoic acid) was first prepared in 1847 by air oxidation of acrolein. Interestingly, after use of several other routes over the past half century, it is tins route, using acrolein from the catalytic oxidation of propylene, that is currently the most favored industrial process. 

Heterogeneous oxidative processes operate at high temperatures (250-450 6C) and are useful for the synthesis of acrolein and acrylic acid from propylene over bismuth molybdate catalysts, the synthesis of maleic and phthalic anhydrides from the oxidation of benzene (or C4 compounds) and naphthalene (or o-xylene) respectively over vanadium oxide,101 arid the synthesis of ethylene oxide from ethylene over silver catalysts.102... 

McCain et al. (17) oxidized CH3—CH=13CH2 over bismuth phospho-molybdate at 450°C. They observed equal distribution of 13C in the terminal carbons of acrolein and also postulated a symmetrical intermediate. They suggested, however, that a symmetrical species could be formed from propylene by either the addition or the abstraction of a hydrogen atom by the catalyst. This would lead to the following scheme. 

The reactor effluent gases are cooled to condense and separate the acrolein from unreacted propylene, oxygen, and other low-boiling components (predominantly nitrogen). This is commonly accomplished in two absorption steps where (1) aqueous acrylic acid (CH2=CHC02H) is condensed from the reaction effluent and absorbed in a water-based stream and (2) acrolein is condensed and absorbed in water to separate it from the propylene, nitrogen, oxygen, and carbon oxides. Acrylic acid may be recovered from the aqueous product stream if desired. Subsequent distilla-... 

Another process for obtaining glycerol from propylene involves the following reactions, where isopropyl alcohol and propylene furnish acetone and glycerin (through acrolein) in good yield (Fig. 2). 

Acrolein and Acrylic Acid from Propylene for Super-Absorbent Polymers, Paints, and Fibres... 

Acrolein and condensable by-products, mainly acrylic acid plus some acetic acid and acetaldehyde, are separated from nitrogen and carbon oxides in a water absorber. However in most industrial plants the product is not isolated for sale, but instead the acrolein-rich effluent is transferred to a second-stage reactor for oxidation to acrylic acid. In fact the volume of acrylic acid production ca. 4.2 Mt/a worldwide) is an order of magnitude larger than that of commercial acrolein. The propylene oxidation has supplanted earlier acrylic acid processes based on other feedstocks, such as the Reppe synthesis from acetylene, the ketene process from acetic acid and formaldehyde, or the hydrolysis of acrylonitrile or of ethylene cyanohydrin (from ethylene oxide). In addition to the (preferred) stepwise process, via acrolein (Equation 30), a... 

The direct oxidation of ethylene is used to produce acetaldehyde (qv) in the Wacker-Hoeclist process. The catalyst system is an aqueous solution of palladium chloride and cupric chloride. Under appropriate conditions an olefin can be oxidized to form an unsaturated aldehyde such as the production of acrolein [107-02-8] from propylene (see Acrolein and derivatives). 

Acrolein and acrylic acid are both made by vapor phase oxidation of propylene. U.S. 6,281,384 (to E. I. du Pont Nemours and Atofina) describes a fluidized bed process, while U.S. 5,821,390 (to BASF) describes an isothermal reactor cooled by heat transfer to a molten salt. U.S. 6,858,754 and U.S. 6,781,017 (both to BASF) describe alternative processes based on a propane feed. Compare the economics of acrylic acid production from propane with production from propylene. Is the conclusion different if the process is stopped at acrolein ... 

Derivation (1) By-product of soap manufacture (2) from propylene and chlorine to form allyl chloride, which is converted to the dichlorohydrin with hypo-chlorous acid this is then saponified to glycerol with caustic solution (3) isomerization of propylene oxide to allyl alcohol, which is reacted with peracetic acid, (the resulting glycidol is hydrolyzed to glycerol) (4) hydrogenation of carbohydrates with nickel catalyst (5) from acrolein and hydrogen peroxide. 

The most industrially significant and well studied allylic oxidations center around the formation of acrylonitrile from ammoxidation (Eq. 7), and acrolein from oxidation (Eq. 8) of propylene ... 

Although substitution was motivated by the availability at that time of propylene and lower cost of the process, it was also a significant improvement in terms of safety, because acetylene is flammable and extremely reactive, carbon monoxide is also toxic and flammable, nickel carbonyl catalysts are toxic, environmentally hazardous (heavy metals), and carcinogenic, and anhydrous HCl (used in the reaction) is toxic and corrosive. However, the new process from propylene carmot be considered inherently safer. Hazards are primarily due to the flammability of reactants, corrosivity of the sulfuric acid catalyst for the esterification step (new solid acids have eliminated this hazard, as discussed in subsequent chapters), small amounts of acrolein as a transient intermediate in the oxidation step, and reactivity hazard for the monomer product. 

For the same reason, the synthesis of acrylic acid from propylene must be carried out in two separate reactors, one for the oxidation of propylene to acrolein and one for the oxidation of the aldehyde to acrylic acid. This is due to the fact that the requirements needed for the two steps make the two reactions incompatible. Acidity is needed in the second step, to favour the desorption of acrylic acid and save it from unselective consecutive reaction, while on the other hand, acidity is detrimental for the first reaction, because it favours the transformation of propylene to undesired products. Therefore, the development of a process for the one-step transformation of propane to acrylic acid will be possible when a catalyst is developed which possesses active sites able to perform quickly the complete transformation of adsorbed propane to the acrylic acid, the latter being the only product which finally desorbs into the gas phase. Accordingly, best performances in the oxidation of propane to acrylic acid have been reported to be obtained on heteropolyoxomolybdates (26), which are known to couple tuneable acid and redox properties. In this case, acid properties may facilitate the desorption of acrylic acid. 

Figure 4. Propylene Yields from Propane Oxidation and Acrolein Yields from Propylene Oxidation vs. Conversion [12],...

Waste products are formed from propane on this catalyst primarily via the second formed acrolein. It is postulated that the acrolein, once formed, readily readsorbs on the catalyst surface, and presumably interacts with a second site which might be either a highly acidic surface site (Mo-0 H" ) or a reduced surface site ( Mo ) or simply by interaction, before desorption, with an adjacent overactive surface site. This scenario is particularly strongly implied by the observed Langmuir-Hinshelwood dependence of waste formation from propylene. 

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