Benchmarking

The benchmark program deals with plants producing pure aromatics (e.g. benzene, toluene or xylenes/C8-aromatics) through recovery from aromatics containing streams using extraction or extractive distillation technology. Worldwide hundreds of aromatic extraction or extractive distillation units are operational in refineries and petrochemical complexes. This benchmark focuses on the latter complexes, which use hydrogenated pyrolysis gasoline as a feedstock. Not included in the benchmark are units for the production of pure aromatics by reaction, such as through hydrodealkylation and disproportionation of alkylbenzenes.

The benchmark comprises butadiene extraction or extractive distillation plants, which produce high purity 1,3-butadiene from raw C4 (steam cracker) feeds. There are more than 100 such plants in the world. Process layouts considered are: (i) two extractive distillations, whereby in the first stage raffinate-1 is the distillate and in the second stage acetylenic components are removed, (ii) single extractive distillation with superfractionation, (iii) single extractive distillation with selective hydrogenation of acetylenic components. The benchmark also includes butane- or butene dehydrogenation plants, which have a different feedstock.

This benchmark is confined to the energy efficiency of propane/ propylene (C3) splitter columns. C3-splitters may be stand alone units or integrated into a refinery or petrochemical complex. The benchmark covers the column including vapor recompression system (heat pump)if present.

This benchmark study deals with the production of cumene from benzene and propylene.Cumene is obtained via the liquid phase alkylation of benzene with propylene. In a subsequent distillation, cumene is recovered from light end products, excess benzene and byproduct diisopropylbenzene (DIPB). The latter is usually treated in a trans-alkylation reactor, where it is reacted with benzene to yield additional cumene. Differences in propylene feedstock purity are taken into account. Catalyst regeneration is excluded from the system boundary.

In hydrodealkylation the essential reaction is the removal of alkyl groups fixed to the benzene ring. The process is primarily used to produce benzene from alkylbenzenes (toluene, xylenes). Since both thermal and catalytic processes are in use, correction methods are applied to account for differences between participants.

The H2/CO benchmark deals with the energy efficiency of the production of hydrogen with/without carbon monoxide from hydrocarbon feedstock ranging from natural gas to naphtha. The benchmark system boundary includes feed pretreatment, synthesis gas generation (SMR/POX/ATR/WGS/…), and product separation and purification.

This benchmark deals with the process of isomerization of (mixed) butane streams into isobutane. Along with the isomerisation unit, the purification of feed and product streams in a depropanizer and/or DIB-column is also included in this benchmark. The feedstock can either be of petrochemical or refinery origin, the product is normally used for the production of fuel oxygenates (e.g. MTBE) or alkylates.

This benchmark comprises the comparison of the energy efficiency of the four major propane dehydrogenation technologies on the basis of licensor information. The system boundary includes feed preparation, the dehydrogenation reaction, propylene work-up, catalyst regeneration, and supporting units such as the refrigeration system. The process has a special characteristic of propane raw material used as an energy source (fuel), which is accounted for in evaluating the energy efficiency.

Pyrolysis gasoline or pygas is produced as a byproduct in steam cracking olefin plants and usually consists of C5- to C10-hydrocarbons. It is a valuable feedstock for the production of aromatics (e.g. benzene), but can also be applied for other purposes such as gasoline production. Because the raw pygas contains unstable or undesired components such as dienes, olefins and sulfur components, the stream is subjected to (2-stage) hydrogenation or hydrotreatment. Because of the custom-made plant layout, general correction methods are used to correct for the differences between participants. The survey is limited to two-stage pygas hydrogenation plants, which fully hydrogenate at least one fraction of the pygas and focuses on plants located at steam cracker facilities.

The benchmark deals with the energy-efficiency of the production of pure acroleine (AC) by oxidation of propene (propylene). The system boundary covers the AC production unit itself, the workup and the offgas treatment. Plants that produce the feed component propene are not included.

Acrylic Acid can be used as the raw material for the production of acrylic esters and for polyacrylates like superabsorbent polymers (SAPs). There are several chemical routes to produce AA, but the most common one is via the partial oxidation of propylene by a two step process in which propylene is first oxidized to acrolein and then further oxidized to AA. Each reaction step usually takes place over a separate catalyst and at different operating conditions. The reaction steps are highly exothermic.

Bisphenol A (BPA) is the main raw material for manufacturing polycarbonate (PC) and epoxy resins. The benchmark covers the synthesis of BPA from acetone and excess phenol via a catalyzed reaction and the separation and purification to a purified crystalline product. The molten BPA may be delivered to the customers or may be further processed in a solidification section to form shapes such as spherical prills, flakes and pellets. The potential recovery and recycling of useful feed and product streams is also incorporated in this benchmark.

The butanediol benchmark deals with the propylene oxide (PO) hydroformylation route with PO and syngas as feedstock.

Most caprolactam units in the world use either phenol or cyclohexane as the raw material. The system boundary of the caprolactam benchmark includes all units required to produce caprolactam from cyclohexanone.

The DMT benchmark covers manufacturing plants producing dimethyl terephthalate from p-xylene by successive oxidation and esterification with methanol. The benchmark includes the purification section: light-ends and heavy-ends removal and purification by crystallization.

The benchmark involves the production of vinyl chloride monomer (VCM) via thermal cracking of 1,2-dichloroethane (EDC) and the production of EDC from ethylene by chlorination and/or oxychlorination. The benchmark focuses on the balanced EDC/VCM process, and also accommodates plants producing EDC only or VCM from import EDC.

The system boundary of the ethylene oxide / ethylene glycol (EO/EG) process comprises all units required to manufacture high purity ethylene oxide and/or high purity ethylene glycols from ethylene and pure oxygen. Part of the ethylene raw material is completely combusted providing some of the process energy requirement. This is accounted for in evaluating the energy efficiency. A correction method applies for the final EO-EG product ratio in order to arrive at a fair comparison between participants.

The methyl diphenyl diisocyanate (MDI) benchmark starts with aniline and formaldehyde as the feed. The system includes three steps: i) production of methylene dianiline (MDA), ii) production of phosgene from CO and Cl2, and iii) the phosgenation of MDA to crude MDI. The MDI precursor aniline is covered by a dedicated PDC benchmark. The purification of crude MDI to final MDI products (monomeric MDI, polymeric MDI, modified MDI) is excluded from the system boundary.

The system boundary of this benchmark includes the production of the intermediate product hydrogen sulfide, the downstream methylmercaptane (MC) reaction itself as well as the workup of the reaction mixture.

This energy benchmark covers the production of mono-, di, and trimethylamine from ammonia and methanol. Because of custom-made plant layouts, corrections are made to account for differences between participants, especially with respect to the product mix.

The benchmark deals with the production of Methyl Isobutyl Ketone (MIBK) from acetone by aldol condensation via diacetone alcohol and mesityl oxide in a single- or multiple-step process.

The benchmark covers Methyl Tertiary Butyl Ether (MTBE) plants with mixed C4 feedstocks (Raffinate-1). Products are MTBE and an isobutylene-free mixed C4 stream. MTBE plants using pure isobutylene as a feedstock (e.g. isobutylene byproduct from the PO/TBA process) are not included. For this specific MTBE process see the PO/TBA benchmark.

This energy benchmark comprises of two steps: i) production of nitrobenzene from benzene and nitric acid, ii) production of aniline by hydrogenation of nitrobenzene. Possible import or export of nitrobenzene has been taken into account. World aniline production is almost completely applied for MDI production, for which a dedicated PDC benchmark exists.

This benchmark covers the production of (plasticizer range) higher branched alcohols from C5 to C14 (branched) olefins via the High Pressure Cobalt technology.

This energy benchmark covers the co-production of phenol and acetone via the well-known cumene-route. Cumene is oxidized by enriched air/oxygen to form cumene hydroperoxide, which is subsequently cleaved into phenol and acetone in the presence of an acid catalyst. Phenol and acetone are then purified to meet market specifications. Because of the custom-made plant layouts, corrections are made to account for the differences between participants.

This benchmark deals deals with the co-production of propylene oxide and styrene monomer via hydroperoxidation of ethylbenzene The ethylbenzene hydroperoxide then, is used to epoxidize propylene to propylene oxide. The resulting byproduct from this epoxidation step (methylbenzyl alcohol) is dehydrated in a subsequent step to form the co-product styrene monomer (SM). The study includes energy-benchmarking of the upstream ethylbenzene (EB) production unit, which benchmark results are reported separately.

The PO/TBA process consists of the following process steps: Isobutane is oxidized to t-butylhydroperoxide, which is used for the epoxidation of propylene to propylene oxide (PO). The resulting byproduct t-butyl alcohol is dehydrated and used for the manufacture of MTBE. PO can be used for manufacturing propylene glycols and propylene glycol ethers. The benchmark comprises all the above-mentioned process steps, and treats them as separate blocks.

The benchmark deals with the production of propylene glycol ethers from propylene oxide and alcohols (methanol, ethanol, propanol, …).

This is a benchmark of toluene oxidation plants, which have benzaldehyde, benzoic acid and phenol as products.

This benchmark deals with the ammonium nitrate / calcium ammonium nitrate (AN/CAN) production process. Pure liquid or gaseous ammonia and a nitric acid solution (ca. 60%) serve as feedstock for the ammonium nitrate production. The ammonium nitrate solution produced is further concentrated, and, after mixing with the appropriate amount of calcium carbonate, treated in a solidification section for the production of solid AN/CAN by prilling or granulation.

The inorganic manufacturing of cyanides can be done in many ways by direct reaction of ammonia with alkanes. From the commercial point of view, most important are the Shawinigan process, the Andrussow process and the BMA process.

This benchmark covers the production of hydrogen peroxide via the anthraquinone auto-oxidation process. To arrive at a fair comparison of energy consumption, corrections have been introduced to account for any on-site use of crude hydrogen peroxide and to account for differences in product concentrations.

The nitric acid benchmark compares plants producing nitric acid (ca. 60 wt%) from ammonia and air. Worldwide, there are several hundred plants. Process steps included are the oxidation of ammonia to nitric oxide, the oxidation of nitric oxide to nitrogen dioxide and the absorption in water. Because NOx-emission might be an important factor, the offgas treatment is also taken into account.

This benchmark covers the production of ‘virgin’ sulfuric acid from elemental sulfur via the S-burning Contact process. Products can either be concentrated sulfuric acid, oleum or SO3 export gas. The process may produce steam as well as power as an utility export.

The system boundary for the benchmark survey of the urea plant covers the production of urea from ammonia and CO2. Pure urea and a virtually pure water stream (process condensate) are the products.

The ABS benchmark deals with the energy efficiency of the Acrylonitrile Butadiene Styrene (ABS) production. The system boundary of the benchmark is flexible towards processes and feedstocks, allowing various processes to participate (e.g. emulsion, solution, suspension, bulk or combined processes). ABS raw materials include the monomers, but also (butadiene) rubbers. Primary ABS is considered as main product, further processing steps starting from primary ABS are not included. The benchmark applies correction factors to account the differences in battery limits, compositions, and conditions of feedstocks and products.

EVOH is a resin with excellent barrier properties produced from ethylene and vinyl acetate. The system boundary of the energy benchmark study includes the acetic acid production through hydrolysis of the byproduct methyl acetate.

Different industrial processes are in operation for the polymerization of caprolactam. Several common names are available for the product poly[imino(1-oxo-1,6-hexanediyl)], like polycaprolactam, polycaproamide, polyamid-6 (PA6) or nylon-6. Correction methods are used in the benchmark to take different PA6 product qualities (e.g. colored or non-colored) into account.

Polycarbonate (PC) is used in a variety of applications such as the fast growing optical media industry (CD and DVD’s), construction, automotive and packaging applications. This benchmark is based on the most commonly used process for PC production, namely the interfacial polymerization process. The polymerization is carried out in a solution of Bisphenol A (BPA) and phosgene at the interface. The production process of phosgene from carbon monoxide and chlorine is also included in this benchmark.

There are two chemical routes used for industrial production of polyethylene terephthalate (PET), the alternating copolymer of terephthalic acid and 1,2-ethanediol (ethylene glycol). One route is the transesterification of dimethyl terephthalate (DMT) with ethylene glycol followed by polycondensation. The other route is the direct esterification of terephthalic acid (TA) with ethylene glycol.

The PVC benchmark deals with the energy efficiency of the polymerization of VCM (vinyl chloride monomer) to PVC according to suspension process (S-PVC). The suspension process represents more than 80% of the global PVC production. The PVC benchmark includes the water purification and solution preparation unit, the suspension polymerization reactors, the stripping and VCM recovery section, the section for dewatering, drying and bulk handling of the PVC product and the waste treatment units. PDC conducts a separate benchmark for the process upstream of PVC production, the production of VCM from ethylene via EDC (ethylene dichloride).

SAPs are materials that can absorb water equivalent to multiple times their mass and are often used as crystalline powders, e.g. in diapers. When SAPs come into contact with aqueous liquids, within a short period of time, the powder absorbs the liquid and forms a gel-like substance. The number of production units for acrylic acid based SAPs worldwide is relatively limited.

More than 60 production facilities in the world produce terephthalic acid (TA) by oxidation of p-xylene. Differences in product purities (e.g. purified terephthalic acid (PTA ) or medium-purity terephthalic acid) between participants are taken into account using correction methods.