Aluminum anchored on g-C3N4 as robust catalysts for Mannich reaction at ambient temperature

•A new reusable Al@C3N4 composite was fabricated by a simple method.•Developing a unique catalyst for synthesizing compounds with pharmaceutical values.•Taking place the reacting under mild condition and green media.•Nanocomposites are characterized by different analysis methods,•Scalable, versatile, and eco-friendly Mannich reactions in good to excellent yields.•The composite system was recycled several times without loss in its activity.