Development of the Common Representative Intermediates (CRI) Mechanism
This presentation is the property of its rightful owner.
Sponsored Links
1 / 18

Development of the Common Representative Intermediates (CRI) Mechanism PowerPoint PPT Presentation


  • 87 Views
  • Uploaded on
  • Presentation posted in: General

Development of the Common Representative Intermediates (CRI) Mechanism. Quantifying ozone formation from VOC degradation. Carter (1994) Maximum Incremental Reactivity (MIR) Scale ‘kinetic reactivity’‘mechanistic reactivity’. Derwent et al. (1998)

Download Presentation

Development of the Common Representative Intermediates (CRI) Mechanism

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Development of the common representative intermediates cri mechanism

Development of the Common Representative Intermediates (CRI) Mechanism


Development of the common representative intermediates cri mechanism

Quantifying ozone formation from VOC degradation

Carter (1994)

Maximum Incremental Reactivity (MIR) Scale

‘kinetic reactivity’‘mechanistic reactivity’

Derwent et al. (1998)

Photochemical Ozone Creation Potential (POCP) Scale

‘kinetic contribution’‘structure-based contribution’

Stedman et al. - national ozone forecasting activities

Highly parameterised chemistry

‘OH reactivity’‘ozone yield’


Development of the common representative intermediates cri mechanism

Degradation of methane (CH4)

CH4 + 8O2→ CO2 + 2H2O + 4O3


Development of the common representative intermediates cri mechanism

Degradation of ethane (C2H6)

C2H6 + 14O2→

2CO2 + 3H2O + 7O3


Development of the common representative intermediates cri mechanism

Unreactive product formation

Branched chain VOC

e.g. methylpropene, t-butanol

unreactive products

+

other products

e.g. acetone

very slow

CO, CO2


Development of the common representative intermediates cri mechanism

VOC degraded in CRI v1

  • 10 ketones (C3-C6)

  • 17 alcohols (C1-C6)

  • 10 ethers (C2-C7)

  • 8 esters (C2-C6)

  • 3 carboxylic acids (C1-C3)

  • 2 other oxygenates (C3)

  • 8 chlorocarbons (C1-C2)

  • 22 alkanes (C1-C12)

  • 15 alkenes (C2-C6)

  • 2 dienes (C4-C5)

  • 1 monoterpenes (C10)

  • 1 alkyne (C2)

  • 18 aromatics (C6-C11)

  • 6 aldehydes (C1-C5)

123 VOC – similar coverage of NAEI inventory as MCM (i.e. 70% of mass emissions)


Development of the common representative intermediates cri mechanism

Coupling with inventory VOC speciation

MCM v3

125 VOC

4,400 species

12,700 reactions

NAEI speciated VOC inventory

650 VOC

CRI v1

123 VOC

250 species

570 reactions

ca. 70% coverage of mass emissions


Development of the common representative intermediates cri mechanism

MCM: broken line

CRI: full line


Development of the common representative intermediates cri mechanism

Development of CRI v2

Objectives of ongoing work

Review representation of chemistry of individual VOC classes – compensating errors ?

Validate mechanism against MCM v3.1

Expand coverage to include a large number of additional alkanes, alkyl-substituted cycloalkanes and alkyl-substituted aromatics

Provide chemistry of additional VOC as modular add-on to MCM


Development of the common representative intermediates cri mechanism

CRI Mechanism

Performance of individual VOC schemes tested against MCM v3.1 (Steve Utembe)

PTM with trajectories for 31 July 1999 used for this purpose:


Development of the common representative intermediates cri mechanism

Simulated ozone using MCM v3.1 with NMVOC emitted entirely as a single alkane


Development of the common representative intermediates cri mechanism

Optimisation of CRI v2 pentane scheme


Development of the common representative intermediates cri mechanism

Cycloalkanes in NAEI speciation – all emitted as cyclohexane


Development of the common representative intermediates cri mechanism

CRI mechanism v2 – concluding remarks

Development of CRI mechanism v2 has commenced with optimisation being performed by comparison with MCM v3.1.

The treatment of individual VOC classes is being considered separately (e.g., alkanes; alkenes; aromatics).

Work to date suggests that the mechanism is improved by defining separate series of intermediates for different VOC classes.

This will result in an increase in size, but should allow a more rigorous description of the impact of different source sectors, and a better foundation for mechanism expansion.


  • Login