D21C 3/04
Pulping cellulose-containing materials: with acids, acid salts or acid anhydrides
Official title: with acids, acid salts or acid anhydrides {(D21C3/003 and D21C3/222 take precedence)}
D21C3/04 (Pulping cellulose-containing materials: with acids, acid salts or acid anhydrides) appears on 221 US grants and 309 published applications in this corpus.
Search patents in D21C- Granted patents
- 221
- Published applications
- 309
- Assignees
- 164
- Inventors
- 543
- Latest grant
- 4 Aug 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1978 | 3 | 0 |
| 1979 | 2 | 0 |
| 1980 | 1 | 0 |
| 1981 | 3 | 0 |
| 1982 | 0 | 0 |
| 1983 | 1 | 0 |
| 1984 | 1 | 0 |
| 1985 | 0 | 0 |
| 1986 | 0 | 0 |
| 1987 | 1 | 0 |
| 1988 | 3 | 0 |
| 1989 | 0 | 0 |
| 1990 | 1 | 0 |
| 1991 | 2 | 0 |
| 1992 | 0 | 0 |
| 1993 | 0 | 0 |
| 1994 | 1 | 0 |
| 1995 | 2 | 0 |
| 1996 | 1 | 0 |
| 1997 | 0 | 0 |
| 1998 | 1 | 0 |
| 1999 | 1 | 0 |
| 2000 | 3 | 0 |
| 2001 | 2 | 1 |
| 2002 | 1 | 3 |
| 2003 | 2 | 1 |
| 2004 | 0 | 2 |
| 2005 | 2 | 4 |
| 2006 | 1 | 2 |
| 2007 | 2 | 2 |
| 2008 | 2 | 5 |
| 2009 | 1 | 8 |
| 2010 | 2 | 10 |
| 2011 | 5 | 13 |
| 2012 | 9 | 8 |
| 2013 | 6 | 12 |
| 2014 | 12 | 29 |
| 2015 | 7 | 24 |
| 2016 | 15 | 20 |
| 2017 | 16 | 14 |
| 2018 | 8 | 11 |
| 2019 | 7 | 18 |
| 2020 | 6 | 10 |
| 2021 | 15 | 27 |
| 2022 | 11 | 24 |
| 2023 | 13 | 19 |
| 2024 | 24 | 17 |
| 2025 | 20 | 17 |
| 2026 | 5 | 8 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
Recent patents
- Optimization of chemical consumption in biomass delignification4 Aug 2026US 12,698,589 B2Sixring Inc.
- Approach to biomass delignification28 Jul 2026US 12,692,653 B2Sixring Inc.
- High yield cooking method14 Apr 2026US 12,601,114 B2AMPPC Finland Oy
- Optimization of chemical consumption in biomass delignification17 Feb 2026US 12,553,180 B2Sixring Inc.
- Method to treat a condensate in a pulping process13 Jan 2026US 12,522,979 B2Nikede Comercio E RepresentaçõEs Ltda.
- Method and system for treating biomass material6 Aug 2026US 2026/0226397 A1Valmet Corporation
- High-bulk ctmp23 Jul 2026US 2026/0210046 A1Billerud Aktiebolag (publ)
- Biomass treatment16 Jul 2026US 2026/0201072 A1Bio-Sep, Inc.
- Novel wheat milling derivative products, methods of making and uses of the same16 Jul 2026US 2026/0201641 A1Archer Daniels Midland Company
- Manufacture of dissolving pulp grade cellulose25 Jun 2026US 2026/0176817 A1Sixring Inc.
Most cited
By later US patents
- Hydrolysis and fractionation of lignocellulosic biomass137US 6,022,419 AMidwest Research Institute · 2000
- Aqueous fractionation of biomass based on novel carbohydrate hydrolysis kinetics76US 6,228,177 B1Midwest Research Institute · 2001
- Method of producing pulp using single-stage cooking with formic acid and washing with performic acid56US 6,156,156 AChempolis Oy · 2000
- Method for fractionation of lignins from steam exploded lignocellulosics to provide fractions with different properties47US 4,966,650 A1990
- Process for recovering and utilizing cellulose using sulfuric acid40US 4,266,981 APurdue Research Corporation · 1981