Propylene production plant

The modified Reppe process was installed by Rohm and Haas at thek Houston plant in 1948 and later expanded to a capacity of about 182 X 10 kg/yr. Rohm and Haas started up a propylene oxidation plant at the Houston site in late 1976. The combination of attractive economics and improved product purity from the propylene route led to a shutdown of the acetylene-based route within a year. 

Although this process has not been commercialized, Daicel operated a 12,000-t/yr propylene oxide plant based on a peracetic acid [79-21-0] process during the 1970s. The Daicel process involved metal ion-catalyzed air oxidation of acetaldehyde in ethyl acetate solvent resulting in a 30% peracetic acid solution in ethyl acetate. Epoxidation of propylene followed by purification gives propylene oxide and acetic acid as products (197). As of this writing (ca 1995), this process is not in operation. 

Significant products from a typical steam cracker are ethylene, propylene, butadiene, and pyrolysis gasoline. Typical wt % yields for butylenes from a steam cracker for different feedstocks are ethane, 0.3 propane, 1.2 50% ethane/50% propane mixture, 0.8 butane, 2.8 hill-range naphtha, 7.3 light gas oil, 4.3. A typical steam cracking plant cracks a mixture of feedstocks that results in butylenes yields of about 1% to 4%. These yields can be increased by almost 50% if cracking severity is lowered to maximize propylene production instead of ethylene. 

The propylene fractionator operates at a pressure of 1.8 to 2.0 MPa with more than 160 trays required for a high purity propylene product. Often a two-tower design is employed when polymer grade (99.5%+) is required. A pasteurization section may also be used when high purity is required. The bottoms product contains mainly propane that can be recycled to the cracking heaters or used as fuel. Typical tower dimensions and internals for a 450,000 t/yr ethylene plant with naphtha feed are summarized in Table 7. 

The petrochemical plant and refinery integration schemes offer lower cost routes to incremental ethylene/propylene production either via revamp modifications or in grassroots application [5,6],... 

As discussed in Section 12.3, the triolefin process to transform propylene to ethylene and 2-butene developed by Phillips135,136 is not practiced at present because of the increased demand for propylene. The reverse process, that is, cross-metathesis of ethylene and 2-butene, however, can contribute to satisfy the global demand for propylene. Lyondell Petrochemical operates a 136,000-t/y (ton/year) plant for the production of propylene.236 In a joint project by BASF and FINA, Phillips metathesis technology will be used to enhance propylene production.237 A similar project was also announced by DEA.238 In a continuous process jointly developed by IFP and Chines Petroleum Corporation, cross-metathesis of ethylene and 2-butene is carried out in the liquid phase over Re207-on-Al203 catalyst (35°C, 60 bar).239,240... 

Yield Pattern. Table XI presents a feed/product summary for a naphtha based billion lb/yr ethylene plant at various severities of 23, 25, and 27 wt % ethylene (once-through basis). The naphtha feed is the same one as referred to earlier (see Table III). It is immediately apparent that feed requirements are increased at lower severities for a given ethylene production rate. Also, production of olefin by-products increases as severity decreases. Note especially the 36% increase in propylene production as severity is dropped from 27% ethylene to 23% ethylene. Butadiene production goes up somewhat, while butylenes production jumps by over 100% going from 27 to 23% ethylene. 

Commercial plants The first SUPERFLEX licensee with a propylene production of 250,000 mtpy is Sasol Technology. Engineering is underway and completion of the unit in South Africa is scheduled for 2005. 

Commercial plants Eleven Oleflex units are in operation to produce propylene and isobutylene. Six of these units produce propylene. These units represent 1.25 million mtpy of propylene production. Three additional Oleflex units for propylene production are in design or under construction. 

Like many countries in the Far East, there is a relatively high demand for propylene. To maximise propylene production from naphtha cracking, the process plant is operated at low severity. In order to maintain design levels of ethylene, more naphtha feedstock is required, with the naphtha requirement being about 3.8 times the weight of ethylene produced. This creates a large demand of about 750,000 to... 

The naphtha produced by the feedstock process is treated in a steam cracker, and the monomers (e.g. ethylene, propylene, butadiene) are recovered. These raw materials are then used for the production of virgin plastic materials. High-boiUng oils can be processed into synthesis gas or conversion coke and then be transferred for further use. All these products have outlets in the local BASF production plants. 

The basis of the economic evaluation is the comparison of operating and investment costs for a membrane reactor with those for a conventional dehydrogenation plant. The return on investment (ROI) and the propylene production costs of the different processes have been calculated. The results are summarised in Table 14.6. Details of the calculations are reported in Ref. [33]. In the calculations a propane price of 130 /tonne and a propylene price of 330 /tonne has been assumed [33]. 

Branched dodecylbenzene is produced by alkylation of polymer tetramer and benzene. The polymer tetramer feedstock is produced in a propylene oligomerization plant using a process such as the UOP catalytic condensation process. Benzene feedstock is typically produced by solvent extraction of reformate or pygas by means of an aromatics extraction process. There is no detailed discussion of DDB production in this entry, as the production of SDBS has been almost entirely phased out. A complete discussion is presented in Ref.. ... 

The cracked gas plant, on the other hand, would likely produce a C4 olefinic mixture for alkylation or chemical manufacture, a propylene product for the same purposes, a propane cut for fuel, and a C2 fraction which is fed to chemical manufacture, or combined with hydrogen and methane used for hydrogen manufacture. 

Propylene. Unlike ethylene, propylene production does not represent the requirement for propylene derivatives. With few exceptions, propylene is not made on purpose but is obtained as a by-product of other processes. More specifically, large quantities of relatively low purity (40-70%) propylene are produced in refineries as a by-product of gasoline manufacture. Additionally, significant quantities of higher purity propylene originate in olefins plants, where ethylene is the primary product. However, only polymer-grade propylene (>99% pure) can in any way be considered an on-purpose product. To better understand... 

There are two main sources of propylene production— refinery and chemical. The former is derived from catalytic cracking and is used mainly for refinery purposes—i.e., polymer gasoline and alkylate. The latter is derived from ethylene plants and is marketed mainly for petrochemical usage. In both cases, the propylene is a by-product and not a directly manufactured product. In 1963 Davis (19) described propylene as the bargain olefin at 2.25 cents/lb and predicted no shortage in sight. He pointed out that 1962 total domestic refinery derived propylene capacity was 17.1 billion lbs annually, and chemically derived propylene was 3.4 billion lbs annually. All of the propylene cannot be recovered economically. Davis estimated that available propylene amounted to 17 billion lbs, of which chemical uses constituted... 

Attention to the propylene shortage had crystallized with the publication of a major study by Stobaugh (56) in 1967, in which he analyzed thoroughly the sources and markets for propylene. He suggested that by 1970 over-all propylene production from both refining and chemical sources would probably not exceed 19 billion lbs, and chemical demand would have increased to 7.5 billion lbs at a value of 2.5 cents/lb. Stobaugh lists both U.S. propylene producers and their plant capacities as well as propylene consumers. 

The general effect, then, as a refiner s ethylene demands increase, is a severity increase on a given feedstock with a resulting decrease in propylene production. At some point he will have to build new facilities. When the new plant is built, the design capacity will be undoubtedly greater than his current needs, and his new unit will be placed on stream —possibly at 70-75% of design ethylene capacity. The old unit would presumably be moth-balled until such time as the new facilities cannot meet production demands. 

The production costs for a propylene oxide plant coproducing isobutylene are shown in Table 7. 

A variety of processes have been used for the production of esters of acrylic (propenoic) acid, including the solvolysis of acrylonitrile with c. H2SO4 and an alcohol. The Reppe process, commercialized by BASF and associated companies, is based on the reaction of acetylene with carbon monoxide, nickel carbonyl and an alcohol. However, the last U.S. operator of this process commissioned a propylene oxidation plant in October, 1982. 

Substitution Main product Natural gas, burned in gas turbine/CH Main product Natural gas, burned in gas turbine/CH Main product Propylene, at plant/RER Natural gas, burned in gas turbine/CH... 

Pri ce. The price of a thermoplastic resin is basically determined by the cost of preparation, which in turn strongly depends on the cost of reagents (monomers, catalysts, etc), the complexity of the manufacturing process, and the dimension of production plants. Aliphatic polyketones, for instance, are made from very cheap raw molecules as ethylene, propylene, and CO their cost is determined by the need for expensive catalysts, based on Pd complexes, and the relatively complex production plant. On the other hand, PEN, which can easily be prepared in the same reactors used for PET, suffers from the difficult availability of its basic monomer dimethyl 2,6-naphthalene dicarboxylate. Most engineering polymers contain aromatic monomers, which are difficult to synthesize and polymerize, with slow and sophisticated mechanisms (condensation, substitution, oxidative coupling). 

COS removal. Propylene produced from cracking plants will contain carbonyl sulfide (COS). When treating propylene to produce a polymer-grade product, one has to meet a stringent sulfur specification. If COS is reported in propylene product, raise the temperature of lean amine to the scrubber 10°F. This usually eliminates the problem. 

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