The default keyboard shortcut to close active tab is Ctrl + W but single-key shortcut will be more convenient if you use numeric keypad. To enable single-key shortcuts, check .
Single-key shortcuts, 1 & 2 are assigned to switch to previous tab & next tab respectively. Shortcut 0 is assigned to zoom in by 10% which is same as + and 3 is assigned to cycle through frames which is not much useful. Change shortcut 0 to close active tab & switch to previous tab and 3 to close active tab & switch to next tab as shown below.
Search keyboard setup for s, 0 and change action for 0 to the following.
Close page & Switch to previous pageSearch keyboard setup for s, 3 and delete shortcut for 3. Create a new shortcut for 3 under application with the following action.
Close page & Switch to next pageIf you want default behaviour of close tab, use the following instead of the above ones.
Close page, 1