Air Products and Chemicals (APD) said late Wednesday that its shareholder Mantle Ridge's proposed nominations of candidates for the chief executive officer and chair roles "should be troubling" to stockholders.

The company's statement is its board's response to activist investor Mantle Ridge's shareholder letter introducing four director nominees, including Executive Chair Dennis Reilley and its proposed CEO candidate, Eduardo Menezes.

Reilley has not held a management position in 18 years and would be coming into a company and industry that have undergone tremendous change in the last two decades, rendering any "experience" that he has as stale, Air Products said.

"Menezes, who has never been a public company CEO, only had responsibility for one region when he worked at Linde, and, as acknowledged by Mantle Ridge, was passed over for CEO at Linde," Air Products added.

Mantle Ridge did not immediately respond to MTNewswires' request for comment early on Thursday.

Air Products' shares slipped 0.4% at the close on Wednesday.

In its shareholder letter, Mantle Ridge urged investors to vote for its nominees "to enhance Air Products' performance and create the long-term value that shareholders deserve." Mantle Ridge said it beneficially owns $1.3 billion of Air Products' outstanding common shares.