Vinyl chloride monomer (VCM) was first produced by reacting acetylene with hydrogen chloride. Until the early 1950s, acetylene-based technology predominated. Due to the energy input necessary to produce acetylene and the hazards of handling it thereafter, ethylene-based routes have since become predominant.
Currently, VCM capacity can be categorized based on the feedstocks acetylene and ethylene. The figure below shows the VCM capacity share of these two feedstocks.
Global VCM Capacity by Feedstocks, 2008
This report examines the competitiveness of VCM produced from different routes and sources of feedstocks. The costs of production of VCM from acetylene (derived from coal/coke), as well as from ethylene using balanced oxychlorination from various feedstocks in selected locations are compared.
For the balanced oxychlorination process, the costs of production of commercial VCM production based on ethylene from an ethane/propane gas cracker in the United States and naphtha cracker in Western Europe are included in the analysis.
Acetylene can be produced by a number of high temperature processes. The classical commercial route is the calcium carbide route in which acetylene is generated by the reaction of calcium carbide and water. In this process, lime is first reduced by carbon (in the form of coke) in an electric furnace to yield calcium carbide:
The calcium carbide is then hydrolyzed to produce acetylene:
The oldest and simplest commercial route to VCM is via the vapor phase addition of anhydrous hydrogen chloride (HCl) to acetylene (C 2H 2) over a mercuric chloride (HgCl 2) catalyst supported on activated carbon.
The majority of commercial VCM technology utilizes direct chlorination of ethylene to produce ethylene dichloride (EDC), followed by pyrolysis to VCM and hydrogen chloride (HCl). In the oxychlorination step, the HCl released by the subsequent pyrolysis of EDC is reacted with ethylene and oxygen to yield additional ethylene dichloride and water. The commercialization of oxychlorination technology paved the way for the so-called “balanced process”, combining direct chlorination, oxychlorination, and EDC pyrolysis reactions. This widely used commercial process utilizes the HCl stream and produces only vinyl chloride and water. The individual chemical reactions are direct chlorination of ethylene to produce ethylene dichloride (EDC), followed by pyrolysis to VCM and HCl and the final reaction shown (immediately below) is the oxychlorination step where hydrogen chloride released in pyrolysis is reacted with ethylene and oxygen to yield EDC and water. The EDC produced in this step is subsequently converted to VCM.
The overall reaction is:
A high proportion of VCM production capacity is based on this technology. However, a number of producers operate unbalanced schemes drawing HCl from other chlorination operations in an adjacent plant. A further variation runs in part on EDC brought in from other sources. Nevertheless, the balanced process is representative of the majority of the industry.
The primary source of ethylene is from steam crackers i.e., by thermal pyrolysis of saturated hydrocarbons in the presence of steam. A variety of feedstocks can be cracked to ethylene, with each yielding a different slate of co-products. In general, the choice of feedstock is dependent on location, and there are considerable regional disparities. Cracker feedstocks can be hydrocarbon gases such as ethane and propane, or oil derived feedstocks such as naphtha and gas oil.
Ethylene production from bioethanol is being planned for use as a feedstock for VCM production. In fact, ethylene has for many years been produced by dehydration of ethanol in Brazil and India, and the Australian chemical industry initiated ethylene-based chemistry by this route before it was feasible to build crackers.
Nexant has modeled the process economics of the major existing and emerging VCM technologies in selected important locations i.e., the United States Gulf Coast (USGC), Western Europe, China, and Brazil, using the leading feedstocks in each venue. The costs for ethylene based VCM are also examined via ethanol dehydration and via conventional steam cracking.
The cases considered for the cost of production analysis are depicted in the table below:
Matrix for VCM Cost of Production Analysis
Commentary on the selected feedstocks used in developing the economic assessments for each region is provided in the report.
Chinese producers have continued to build new acetylene based VCM/PVC plants near its coal producing regions in the South and West. The report includes the following Cost of Production Estimate Tables, from which Cost of Production Estimates for ACETYLENE-based VCM in China have been developed:
Two coal price cases were modeled in order to represent the range of production costs of the acetylene route, because the coal prices fluctuated so much during the first half of 2008.
The report includes the following Cost of Production Estimate Tables, from which Cost of Production Estimates for ETHYLENE-based VCM in the USGC, Western Europe and Brazil have been developed:
The production cost estimates are based on 2Q, 2008 when the Brent crude oil price was high. However, the economic for these alternative routes may be less favorable than the conventional production at lower crude oil price.
To test the impact of crude oil and consequently other raw material prices on VCM production costs, the sensitivity analysis was performed for both acetylene and ethylene production routes. Costs of production were estimated on a series of these material prices as follows. This represents the past raw material price and the potential price in the future.
Utilities costs are adjusted along with the change of the crude oil price, while other costs remain unchanged.
The results of this analysis are illustrated and discussed.
VCM is used almost exclusively to produce PVC. PVC can be used in a multitude of applications by employing a number of fabrication methods including extrusion, calendaring, injection molding, blow molding, and coating. Most PVC is processed by extrusion to make pipe, siding and window or door profiles, wire and cable insulation and rigid film or sheet.
Other applications include chlorinated solvents and polyvinylidene chloride, however the volumes involved are insignificant relative to PVC production.
The market section provides a detailed understanding of regional dynamics (U.S., Western Europe, and Asia Pacific).
These reports are for the exclusive use of the purchasing company or its subsidiaries, from Nexant, Inc., 44 South Broadway, White Plains, New York 10601-4425 U.S.A. For further information about these reports contact Dr. Jeffrey S. Plotkin, Vice President and Global Director, PERP Program, phone: 1-914-609-0315; fax: 1-914-609-0399; e-mail: email@example.com or Heidi Junker Coleman, phone: 1-914-609-0381, e-mail address: firstname.lastname@example.org
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