Unexpected quenching effect on new particle formation from the atmospheric reaction of methanol with SO ₃

Abstract

Despite the high abundance in the atmosphere, alcohols in general and methanol in particular are believed to play a small role in atmospheric new particle formation (NPF) largely due to the weak binding abilities of alcohols with the major nucleation precursors, e.g., sulfuric acid (SA) and dimethylamine (DMA). Herein, we identify a catalytic reaction that was previously overlooked, namely, the reaction between methanol and SO3, catalyzed by SA, DMA, or water. We found that alcohols can have unexpected quenching effects on the NPF process, particularly in dry and highly polluted regions with high concentrations of alcohols. Specifically, the catalytic reaction between methanol and SO3 can convert methanol into a less-volatile species––methyl hydrogen sulfate (MHS). The latter was initially thought to be a good nucleation agent for NPF. However, our simulation results suggest that the formation of MHS consumes an appreciable amount of atmospheric SO3, disfavoring further reactions of SO3 with H2O. Indeed, we found that MHS formation can cause a reduction of SA concentration up to 87%, whereas the nucleation ability of MHS toward new particles is not as good as that of SA. Hence, a high abundance of methanol in the atmosphere can lower the particle nucleation rate by as much as two orders of magnitude. Such a quenching effect suggests that the recently identified catalytic reactions between alcohols and SO3 need to be considered in atmospheric modeling in order to predict SA concentration from SO2, while also account for their potentially negative effect on NPF.

Global optimization of chemical cluster structures: Methods, applications, and challenges

“…The development of GO as implemented in ABCluster, has eliminated this obstacle to a large extent, making a series of productive NPF studies possible [32, 96, 167, 172–197] and revealing valuable insights into atmospheric chemistry (see Figure 7 for some examples). ABCluster has been regarded as a standard tool in this field [198–200].…”

“…Later, GO with first‐principles methods were carried out for the first time for gas phase atomic clusters (B3LYP) [28] and Ge 12 − 20 (PBE) [29] in 2005, for surface‐supported cluster Ag 1 − 4, 6, 8, 10 @MgO(100) (PBE) [30] in 2007, and for molecular cluster H(H 2 O) 1 − 4 (B3LYP) [31] in 2010. Since 2016, clusters in GO studies go beyond one‐ or two‐component systems and become larger and more complicated, like (CH 3 OSO 3 H) x (H 2 SO 4 ) y ((CH 3 ) 2 NH) z [32], Pt 7 H 10 CH 3 @α‐Al 2 O 3 (0001) [33], and Ag 55 @ZrO 2 /SiO 2 [34]. These exciting changes enable GO of clusters to be applied to more realistic chemical problems.…”

Reactions of Criegee Intermediates are Enhanced by Hydrogen‐Atom Relay Through Molecular Design

“…DHAT reactions are important in the atmosphere, possibly participating in new particle formation . However, some atmospherically relevant DHAT reactions are too slow to be measured within laboratory time scales .…”

Structural Effects of Amines in Enhancing Methanesulfonic Acid-Driven New Particle Formation

“…[1][2][3][4][5][6] Atmospheric new particle formation (NPF) through gas-to-particle conversion constitutes over half of the global aerosol budget. [1][2][3][4][5][6][7][8][9][10][11][12] It is widely accepted that gaseous sulfuric acid (SA) formed from SO2 oxidation plays a key role in atmospheric NPF, 3,5,6,[13][14][15][16][17][18][19][20][21][22] and a broad variety of atmospheric compounds such as ammonia, amines, and organic acids efficiently enhance SA-driven NPF by stabilizing the newly formed molecular clusters. 3,13,14,20,[23][24][25][26][27][28] However, significant gaps remain between the observed particle formation rates in the field and laboratories and the rates predicted by simulations.…”