Exhibit 21.1
SUBSIDIARIES OF ECOVYST INC.

ENTITY
JURISDICTION
Ecovyst Inc.
Delaware
Ecovyst Holdings Inc.
Delaware
Ecovyst Midco I Inc.
Delaware
Ecovyst Midco II Inc.
Delaware
Ecovyst Catalyst Technologies LLC
Pennsylvania
Delpen Corporation
Delaware
Eco Services Operations Corp.
Delaware
Chem32 LLC
Delaware
Commercial Research Associates, Inc.
Pennsylvania
Zeolyst International1
Kansas
Ecovyst International Holdings Inc.
Delaware
New Dutch Catalyst Holdco 1 B.V.Netherlands
New Dutch Catalyst Holdco 2 B.V.Netherlands
New Dutch Catalyst Holdco 3 B.V.Netherlands
Ecovyst Catalyst Technologies UK LtdUnited Kingdom
Ecovyst Zeolites B.V.Netherlands
Zeolyst CV2
Netherlands
Ecovyst Catalyst Technologies Brazil LtdaBrazil
PT Ecovyst Indonesia3
Indonesia
Ecovyst International Cooperatie UANetherlands
Ecovyst International B.V.Netherlands
Ecovyst International, Inc.
Pennsylvania
Ecovyst Systems Inc.
Pennsylvania
Ecovyst Pennsylvania Inc.
Pennsylvania

1Represents a joint venture company of which the registrant indirectly owns 50% of the voting equity.
2Registrant indirectly owns 50% of the voting equity.
3Registrant indirectly owns 88% of the voting equity.