Could not execute SQL: Unknown column 'duc' in 'where clause'

SELECT a.id, a.title, a.alias, a.catid, a.thumb, a.introtext, a.created, a.created_by, a.hits, c.name AS category_name ,a.title,a.alias,a.introtext,a.fulltext,a.meta_title,a.meta_key,a.meta_desc FROM td24g_articles AS a INNER JOIN td24g_articles_categories AS c ON c.id = a.catid WHERE a.catid IN (duc) AND a.enable = 1 AND c.enable = 1 ORDER BY a.title LIMIT 0,9999