<SEC-DOCUMENT>0001708035-23-000044-index.html : 20240208
<SEC-HEADER>0001708035-23-000044.hdr.sgml : 20240208
<ACCEPTANCE-DATETIME>20231130144103
<PRIVATE-TO-PUBLIC>
ACCESSION NUMBER:		0001708035-23-000044
CONFORMED SUBMISSION TYPE:	CORRESP
PUBLIC DOCUMENT COUNT:		2
FILED AS OF DATE:		20231130

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Ecovyst Inc.
		CENTRAL INDEX KEY:			0001708035
		STANDARD INDUSTRIAL CLASSIFICATION:	CHEMICALS & ALLIED PRODUCTS [2800]
		ORGANIZATION NAME:           	08 Industrial Applications and Services
		IRS NUMBER:				813406833
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		CORRESP

	BUSINESS ADDRESS:	
		STREET 1:		300 LINDENWOOD DRIVE
		CITY:			MALVERN
		STATE:			PA
		ZIP:			19355
		BUSINESS PHONE:		484-617-1200

	MAIL ADDRESS:	
		STREET 1:		300 LINDENWOOD DRIVE
		CITY:			MALVERN
		STATE:			PA
		ZIP:			19355

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PQ Group Holdings Inc.
		DATE OF NAME CHANGE:	20170531
</SEC-HEADER>
<DOCUMENT>
<TYPE>CORRESP
<SEQUENCE>1
<FILENAME>filename1.htm
<TEXT>
Document 1 - file: filename1.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>2
<FILENAME>letterheada.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 2 - file: letterheada.jpg

</DOCUMENT>
</SEC-DOCUMENT>