Older dogs usually chew to release tension. There are several things you can do to help your dog feel more at ease. Try to avoid emotionally charged departures. The greater fuss you make, the more anxiety you create. Establish your leadership through training.
Dogs are more secure knowing they have a leader.
Do not give in to his demand for excessive attention when you are home. The more you give, the more he will want and, when you are not there, he will be frustrated. Do not isolate your dog as punishment for chewing. This will create more tension and lead to more chewing. Do not physically punish him for chewing.