** Brokerage Piper Sandler says it expects lower EBITDA in Q4 2024 and 2025 for chemical companies due to structural issues in the EU and Asia; says U.S. operations may "carry most of the weight"

** Says it will be hard for the companies to generate significant earnings momentum over the next 12-18 months

** Piper Sandler downgrades Dow Chemical DOW.N and LyondellBasell LYB.N to 'neutral' from 'overweight', and cuts PTs to $53 from $60, and $95 from $112, respectively

** Expects Ecolab ECL.N (maintain "overweight", PT cut to $270 from $305) and Olin OLN.N (maintain "overweight", PT cut to $41 from $51), among others, to be in best position to expand earnings partially on lesser degree of overcapacity in their markets

** Brokerage says it does not expect a rebound in China's chemical demand growth and U.S. pricing and margins will not be enough to drive company earnings

** Says stimulus in China and the EU will have more gradual impact than anticipated and might not address overcapacity

(Reporting by Seher Dareen in Bengaluru)

((Seher.Dareen@thomsonreuters.com;))