Date post: | 27-Mar-2015 |
Category: |
Documents |
Upload: | alexa-oleary |
View: | 213 times |
Download: | 0 times |
Feasibility study on China‘s mercury-free
catalyst R&D
FECO/ MEP/ChinaOctober, 2011
Dr Sun Yangzhao
Content
1. PVC industry developments and mercury
management status in China
2. Project background and progress
3. Mercury pollution control policies
4. Difficulties and challenges
5. Next steps
1.PVC production and mercury management in China
PVC plastic is widely used in industry, agriculture, national defense and chemical construction materials, etc in China.
Chinese PVC production can be divided in two categories: carbide method and ethylene method.
For the carbide route, CaC2 is used as raw material, and activated carbon with HgCl 2 serves as catalyst for the production of VCM which will be further used to make PVC.
Table 1: PVC Data for China 2009 (Source MIIT, 2010)
Type of Production # ofFacilities
PVC production(million tonnes)
% of total production
Carbide-based 94 5.8 63.4
Ethylene 10 3.35 36.6
Total 104 9.15
Mercury in carbide based process
Currently for one ton PVC produced in China:
1.2 kg of HgCl 2 catalyst consumed on average (as 11% of HgCl
2 content).
For 5.8 million tons of PVC produced in 2009, around 7000 t
ons of mercury catalyst used, comprising:
770 tons of HgCl 2 and 570 tons of mercury were used (MIIT, 2
010)
Carbide-based PVC production consumes around 60 % of
China’s total annual mercury use.
M ercury flow chart in carbide PVC production
HCl composition
acetylene process
HCl
C2H2
VC composition
Compound absorption
Compression distillation
Monomer tank
Hg bearing waste acid
Hg remover
Hg absorbed activated
carbonworn catalyst
potential mercury pollution source
Catalyst Effectiveness
Sublimation and intoxication causes reduction of catalyst
effectiveness.
When it decreases to certain level, catalyst need to be replaced
and inactivated catalyst becomes worn catalyst.
Usually waste catalyst contains 3-4.5% mercury.
After Hg remover, part of the sublimated HgCl2 will enter the
worn acid and alkali and get emitted.
Necessity of carbide process
Carbide PVC production uses lots of mercury, but it remains necessary :
Chinese energy structure characterized as "lack oil, poor in gas and rich in coal"
Ethylene method can hardly meet the need of PVC industry alone
Carbide PVC industry pays high attention to mercury pollution administration.
Emission reduction measures for carbide PVC production
The industry has adopted the following measures to reduce mercury use and emissions:
low mercury subsititute for high mercury one ;activated carbon in mercury remover to absorb mercury in gas phase ;waste acid recycled by desorption device, a few of which are used to neutralize worn alkali ;waste alkali used to neutralize waste acid, and collected together with other waste liquid for central treatment;waste catalyst, activated carbon and other waste sludge are sent to certified orgnization for central treatment.
One Carbide-based PVC Producer
2. Project background and progress
UNEP has provided funds for China to carry out PVC project through small grants program. The project is now on its second phase.
Phase I “Communication and Deliberation of the Practice of Mercury Use and Emission Reduction during PVC production” agreement was signed in January of 2009.
Phase II “Feasibility study on China‘s mercury-free catalyst R&D ” agreement was signed in April of 2011.
Target and Research Results of Phase I
Phase 1 - Overall Target: To reduce mercury use in Chinese PVC industry
Duration : From Jan. 2009 to Sep. 2009Activities and results : Organization of “Workshop on Mercury Reduction in Carbide
PVC Production”
Investigation and study on mercury use and reduction status in Chinese PVC production by acetylene
Analysis of administrative and policy needs mercury use in this industry.
Target and Progress of Phase II
Phase 2 Overall Target - To promote mercury free catalyst development and use in VCM production.
Implementation duration : April 2011-December 2011
Main activities : Organization of “Project workshop on Mercury free catalyst dev
elopment feasibility”;
Develop a feasibility study report on mercury-free catalyst research and development, including identification of near-term and long-term activities.
Project workshop on Mercury free catalyst development feasibility, 19-20 September 2011
•Approximately 40 participants from Chinese government and industry, representatives from the international community
•Agenda :• International mercury convention negotiation process
• China PVC industry update
• Updates of mercury-free catalyst R&D home and abroad
•Outcomes:• Exchange of ideas on demands for and challenges to develop
mercury-free catalyst technology.
• Expert team proposed draft criteria for a peer review process.
Wide-spread use of low Hg catalyst
By adoption of low Hg catalyst, mercury removal and centralized treatment of waste, producers are able to meet the national emission limit requirements.
time target
2012 50% use of low Hg catalyst per VCM production
25% less use of HgCl per ton of PVC at averagewhole industry realizes sound collection of worn Hg catalystindustrialization of efficient collection technology of VC composing gas phase 50% use of HCl deep desorption technology
2015 whole industry uses low Hg catalyst50% less use of HgCl per ton of PVC at average100% recycling of worn low Hg catalystHigh efficient Hg recycling technology penetration rate of 50%over 90% penetration rate of HCl deep desorption technology100% use of NaHS treatment for Hg bearing wast water
Mercury free catalyst R&D progress
Currently, carbide PVC producers are working with research institutes on following research:
to carry out acetylene VCM fluidized bed technology, i.e. mercury-free catalyst, supportive process, reactor.
catalytic system of hydrogen chloride of acetylene to produce VCM; R&D of gas-liquid mercury-free catalyst.
enterprise-based mercury-free catalyst R&D and engineering pilot platform is taking initial shape.
2007 – Industry restructuring directory list (2007) specifies HgCl2 catalyst under restricted category.
Encourages oxychlorination of ethylene to replace carbide method ; For new, modified or expanded PVC installation must reach the scale
of over 300,000 tons a year.
2009 – MEP released clean production standards for chloralkali industry (carbide PVC), which specifies technological requirements to produce VCM in a clean manner.
April 2011 – 12th Five Year Plan for Comprehensive prevention and control of heavy metal pollution was approved and promulgated by the State Council (applies to lead, mercury, cadmium, chromium and arsenic).
3. Relevant industry mercury pollution control policy
Indicator Class 1 Class 2 Class 3
I. process and equipment requirement
1. For HCl desorption device use HCl deep desorption technoogy
use HCl regular desorption technology
2. For mercury catalyst use low Hg and waste acid water treatme
nt technology
use low Hg catalyst technology
3.VC mercury recycling requirements VC mercury recycling treatment
II. resource and energy use indicatorsHg catalyst consumption per unit of product(kg/t)
1.2 1.3 1.4
III. Pollutant generation indicator (before end treatment)waste water generation per unit of product
12 35 40
THg per unit waste water(g/t) 1.5 1.8 2.0
2009 MEP Clean Production Standards for
Chloralkali Industry (carbide PVC)
Clean Production Auditing Standard
Notification on Enhancing Hg Pollution Prevention and Control in Carbide PVC industry.
Issued by MEP - January 19 2011 Purpose was to enhance pollution prevention and control management framework in carbide PVC production, Hg catalyst production and treatment of worn catalyst.Notification requires :
i. Increased awareness of the importance of pollution control in carbide PVC production
ii. Promotion of low Hg catalyst and effective reduction of Hg emissions
iii. Tighter environmental management and strengthened monitoring measures
iv. Strengthened policy support and supportive measuresv. Increased role of industry association in education and training.
Hg and Hg compound bearing waste or polluted waste are already listed into State Hazardous Waste List
MEP is formulating Hg bearing pollutant prevention and control technical policy, which includes worn Hg catalyst.
Hg bearing waste management
Difficulties and Challenges Ahead
(1 ) Legislation and Enforcement
inadequate force in industry restructuring as well as in promoting and applying new reduction technology and new material
administrative weakness in mercury and HgCl2 catalyst production and supply
production operation needs to be standardized.
(2) Capacity basic situation and understanding is not clear lack of monitoring/surveillance of mercury discharge.
Difficulties and Challenges Ahead
( 3 ) Technology Application of low-mercury technology needs to be further im
proved and researched Need of alternative techology:
mercury-free catalyst is still under research and development
economic and other effects of application need to be taken into consideration before wide-scale adoption.
HCl desorption is only partly applied among enterprises.
Difficulties and Challenges Ahead
( 4 ) Financing
involves a wide range and large number of enterprises most enterprises are small-scale with limited profit margins alternative technologies are highly specialized and expensive.
As a developing country, China is facing huge shortage of labor-power, material and financial power.
Next steps for Carbide based PVC Production
Phase1 (Jan 2010~Jan 2012)Activity 1: Raise understanding of mercury pollution risks amongst local environmental protection bodies and industry.Activity 2 : Develop emission inventory. Activity 3 : Study the evaluation and application standards of low-mercury and non-mercury catalyst. Activity 4 : Set up reduction plan and targets across PVC industry.
Phase 2( Jan. 2012~Dec.2013
Activity 5: Research mercury alternative technology and pilot application, apply mercury reduction measures and standardize administration.
Activity 6: Initiate assessment and operation guidance for above.
Conclusion
Although the Chinese central government has paid a lot of attention to mercury pollution prevention and control in the VCM sector, it is still facing a lot of difficulties and uncertainties with spreading information on the low-mercury catalyst and the researching & development of free-mercury catalyst.
We hope for more support, including finance and technologies from developed countries!
Acknowledge
Special thanks extended to the following:
Chemicals Branch, DTIE of UNEPDepartment of International Cooperation, MEPDepartment of Pollution Prevention and Control, MEPChemical Registration Center, MEPChina Petroleum and Chemical Industry Association