Arq, Inc.

United States

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No. )

Check the appropriate box:

ARQ, INC.

(Name of Registrant as specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

April 28, 2026

Dear Fellow Stockholder:

On behalf of the Board of Directors, we are pleased to invite you to the 2026 Annual Meeting of Arq, Inc.'s Stockholders, which will be held at 9:00 a.m. (Mountain Time) on June 10, 2026. We are pleased to announce that this year’s Annual Meeting will again be a virtual meeting via live webcast on the internet. You will be able to electronically attend the Annual Meeting and vote during the meeting by visiting www.virtualshareholdermeeting.com/ARQ2026. To enter the Annual Meeting, you will need the 16-digit control number located on the Notice of Internet Availability of the Proxy Materials, on your proxy card or in the instructions that accompanied your proxy materials. We recommend that you log in at least 10 minutes before the meeting to ensure you are logged in when the meeting starts.

At the Annual Meeting, you will be asked to elect six directors named in the Proxy Statement, provide your advisory approval of our executive compensation, ratify the appointment of Baker Tilly US, LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026, approve the Arq, Inc. 2026 Omnibus Incentive Plan, and approve the Ninth Amendment to the Company's Tax Asset Protection Plan.

The accompanying notice of meeting and this Proxy Statement provide specific information about the Annual Meeting and explain the various proposals. Please read these materials carefully.

Thank you for your continued support of and interest in our Company.

President and Chief Executive Officer

Arq, Inc.

8051 E. Maplewood Ave., Ste. 210

Greenwood Village, Colorado 80111

Telephone: (888) 822-8617

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Our Stockholders:

The 2026 Annual Meeting of Stockholders (the “Annual Meeting”) of Arq, Inc., a Delaware corporation ("Arq" or the "Company"), will be held at 9:00 a.m. (Mountain Time) on June 10, 2026 via live webcast, which can be accessed by visitingwww.virtualshareholdermeeting.com/ARQ2026, where you will be able to electronically attend the Annual Meeting and vote on the following:

1. To elect six directors of the Company named in this Proxy Statement;

2. To approve, in an advisory vote, our executive compensation;

3. To ratify the appointment of Baker Tilly US, LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026;

4. To approve our 2026 Omnibus Incentive Plan;

5. To approve the Ninth Amendment of the Company's Tax Asset Protection Plan; and

6. To transact such other business as may properly come before the Annual Meeting or any postponement or adjournment thereof.

Stockholders of record at the close of business on April 14, 2026 are entitled to notice of and to vote at the Annual Meeting. The approximate date on which the proxy materials, including this Proxy Statement, are first being made available to stockholders is April 28, 2026.

The Annual Meeting will be held virtually and our stockholders are cordially invited to attend the Annual Meeting via live webcast. Stockholders of record will be able to electronically attend the Annual Meeting, ask questions and vote during the live webcast of the meeting by visitingwww.virtualshareholdermeeting.com/ARQ2026 and entering the 16‐digit control number included in our Notice of Internet Availability of the Proxy Materials, on your proxy card or in the instructions that accompanied your proxy materials. We recommend that you log in at least 10 minutes before the meeting to ensure you are logged in when the meeting webcast starts. For specific instructions, please refer to "General Matters" in this Proxy Statement and the instructions on the proxy card.

Please call our toll-free number (888) 822-8617 if you have questions concerning the meeting.

By Order of the Board of Directors,

President and Chief Executive Officer

April 28, 2026

Important Notice

Regarding Internet Availability of Proxy Materials for the Annual Meeting of Stockholders to be Held on June 10, 2026

The Company's Proxy Statement and Annual Report to Stockholders are Available at: www.proxyvote.com

TABLE OF CONTENTS

Please note that website references throughout this document are provided for convenience only, and the information on our website is not part of this Proxy Statement and is not incorporated by reference herein.