These are multicast addresses - 224.0.0.0 through 239.255.255.255.
The range from 224.0.0.0 to 224.0.0.255 (or 224.0.0.0/24) is designated for multicasting on the local LAN only.
224.0.0.251 is the Multicast DNS address.
224.0.0.22 is used by the IGMP Version 3 (Internet Group Management Protocol).
More details here:
http://www.iana.org/assignments/multicast-addresses/
SD