Prospects  of  Supply  and  Demand  of
          Synthetic  Rubber  Raw  Materials Styrene  and  Butadiene
                             By Zhou Wenrong
Styrene and butadiene  are  two  monomer  raw  materials  of  synthetic
rubbers with the greatest consumption. The output of synthetic rubbers
based on these two monomer raw materials accounts for  around  80%  of
the total in the world.
1. Present status
China started the production of styrene and butadiene in the late  50's
with a  purpose  of  providing monomer  raw  materials  for  the    13
500 t/a SBR unit of Lanzhou Chemical  Industrial  Corporation.   After
more than 30 years's development, the capacity of styrene and butadiene
in China reached 300 000 t/a and 470 000 t/a and  the  output  reached
256 000 tons and 333 000 tons in  1995.   The  capacity  of  synthetic
rubbers (including SBS and latex) was 520 000 t/a and the  output  was
498 000 tons in 1995.
  Due to the constraints in the supply of  raw  materials  styrene  and
butadiene, synthetic rubbers still can not satisfy the domestic demand
. The output can only meet two- thirds  of  the  domestic  consumption.
China has become the biggest net importer of synthetic rubbers in  the
world. The import amount increased from 50 000 tons in 1990 to 310 000
tons in 1995. The export amount is, however, less than  one- tenth  of
the import amount. Table 1 shows the production and import of  monomer
raw materials in China. It can be seen from the table that the rate of
self-sufficiency was only 45% for styrene and around 80% for butadiene
in 1995.
Table 1 Production and Import of Monomer Raw Materials
               in China from 1991 to 1996
                                                     ('000 t)
                               Styrene          Butadiene
  Total output                  1 330             1 890
  Output in 1996                  300               410
  Total import amount           1 240               200
  Import amount in 1996           390                40
2. Supply and demand
(1) butadiene
The raw material route for butadiene production in China is similar  to
advanced countries in the world. It has gone through a transition from
the alcohol  process  and  the  butene  or  butane  oxydehydrogenation
process to the C4 solvent extraction process.
The alcohol process in China started in 1960.   Butadiene  produced  at
that time was used as monomer raw material in the SBR unit and the NBR
unit of Lanzhou Chemical  Industrial  Corporation.   The  process  was
outdated and the production cost was high. The process  was  therefore
eliminated in 1990.
The  butene  oxydehydrogenation  process  is  a  commercial  production
technology developed by China itself. It has solved the  raw  material
supply for the initial massive expansion  of  BR   production.     The
first 16 000 t/a butadiene unit using  the  butene  oxydehydrogenation
process was completed  and  put  into  operation  in  Beijing  Yanshan
Petrochemical Corporation in 1971. In the later  years  6  such  units
  were  constructed  in  other  producers  such  as  Shanghai   Gaoqiao
Petrochemical Corporation and Shandong Qilu Petrochemical Corporation.
The total capacity is more than 100 000 t/a. However,   only  3  units
with sufficient butene supply have maintained long- cycle  and  stable
operations. The biggest single unit capacity is 27 000 t/a.  With  the
development of the ethylene industry, the process is  expected  to  be
gradually replaced by the C4 solvent extraction process.
The extraction of butadiene from cracked C4 in China  also  started  in
  the  10  000  t/a  butadiene  unit  of  Lanzhou  Chemical  Industrial
  Corporation.     The   process   is   developed   from   the   butene
oxydehydrogenation process  used  in  Shanghai  Gaoqiao  Petrochemical
Corporation and Hunan Yueyang Petrochemical Corporation  to  meet  the
requirements of cracked C4 raw material.
The imported 300 000 t/a ethylene units have provided abundant  C4  raw
material for the massive butadiene  production.   China  imported  the
advanced technology from a Japanese company and  constructed  a 45 000
t/a butadiene unit using DMF as solvent.  Another  4  butadiene  units
were completed in Daqing, Qilu, Yangzi and Shanghai in the  80 .   The
total capacity of butadiene in China  reached  316  000  t/a  and  the
output reached 258 000 tons in 1990.
With the construction of new ethylene units, China set up&n